Firstly are you really sure that the problem is with the wi-fi signal.
The reason I say this is because if it's getting 3 bars on the wi-fi that is normally quite acceptable and shouldn't really cause that many problems. My main laptop regularly has 3 bars, and my PC sometimes goes down as low as 1 due to a lot of the radio interference we have in the area (we live right below one of the RAF monitoring stations in Shropshire so we get a lot of interference from that on all radio frequencies).
Wi-fi can be really funny, it's the same as with any radio technology - I completed my City & Guilds RAE and have a full amateur radio licence and due to this I know a bit about what can affect radio signals and believe me there is a lot, and also you can find that one device will get a perfect signal whilst another device can get a poor one, although I would hardly call 3 bars a poor signal.
The main things that will affect the receiver is the position and length of the antenna. In a laptop you don't normally see the antenna because it's normally run around the edging of the screen. Depending on where the antenna is it can affect the signal quality, for example if it's next to something that is giving out a load of EMF (electro-magnetic fields) that isn't probably shielded (like a hard drive, or CPU) then this can cause very severe problems with the signal - same as when you put a radio near a computer and you get that awful noise. Most computers should be shielded enough from the wi-fi to stop this from happening though.
The actual position - or polarisation of the antenna can also affect signal quality. Some antennas have vertical polarisation and others have horizontal, some are omni (both) and some can be turned to suite your needs. Polarisation works on the orientation of the antenna, if you think of a stick antenna, vertical is when it's straight up (the main way most people put their antenna) and vertical is when the antenna is sidewards. I presume that in the laptop you will not be able to alter the polarisation (it's most probably a vertical loop going round the inside of the screen), however on quite a few routers your can change the polarisation, if the router has antenna's on it, try turning them around and you should notice either the signal gets stronger or weaker depending on whether it's vertical or horizontal. This polarisation does have a very good use when you want to block unwanted signals. For example in some hilly areas you may notice TV aerials on houses some are one way round where as others look like they've been mounted on their side, this is not a mistake this is deliberate, in some hilly areas they have repeater stations set up to repeat the TV signal round the valleys, and by setting one repeater up as a vertical transmitter and the next up as a horizontal transmitter they can transmit the signal on the same frequency without interfering with the other signal, this also happens a lot on satellite TV when tuning in some channels are on vertical and some horizontal and the LNB turns the antenna to the correct orientation, this is so they can fit more channels onto the satellite bandwidth.
Finally an antenna has to be a certain length to be of any use, you have things like quarter wave, half way or full wave. The length is the length of the frequency you are trying to receive for example standard fm radio is about 100mhz which is about 3m so a full wave antenna for FM radio should be about 3m long (1/2 is about 1.5m and quarter wave is 0.75m), this gets shorter the further up the frequency you go - amatuer radio uses about 144mhz which is about 2m and wi-fi uses 2400Mhz (2.4Ghz) which a full wave is about 12.5cm. However in a laptop you really shouldn't have to worry about any of these measurements as the antenna wire should be pre-cut to them lengths, it could be that one laptop is closer to 12.5cm long antenna than the other and that may be why the signal is a little bit weaker, but the signal being only 2 bars weaker really shouldn't be causing the problems you are saying.
I would say that the problems you are having are possibly software issues, looking at the spec of the machine it certainly seems fast enough to cope easily with things like Skype, I know some of those "netbooks" certainly struggle with a lot of things and can be a nuisance, but looking at the spec I can tell it's certainly no netbook. There are a few things you can try to eliminate software issues which no doubt if you call up the tech company they will probably tell you one of the same things.
The first thing I'd suggest you try if your quite good with technology - download a Linux Live CD - like Puppy Linux, and attempt boot the laptop from that. Set Puppy Linux up to connect to the wi-fi (some tech knowledge may be required here) and try using it under Puppy, the wi-fi drivers in Puppy actually give you a number rather than bars as to how strong a signal it is receiving (at present in my house I have two routers - one is receiving at 39/70 (just over 50%) - this router is on the other side of my house and is my main internet router and my other router is getting 61/70 - this one is about 6ft from this laptop).
After testing it on a linux live cd for a while if it seems to work fine then it is most probably some kind of driver or software issue within Windows, if however it does the same in Linux it's highly likely to be some kind of hardware issue. If it is a hardware issue, shut Linux down - on shut down it may ask if you want to save settings to the hard drive - don't save the settings or anything, then remove the CD and get it fixed under warranty, although I highly suspect that you'll find it is software related rather than hardware. I've fixed numerous PC's over numerous years and a lot of the time I find it to be some kind of problem with Windows rather than the actual hardware.
Now if it is software I'll tell you exactly what the tech guys will tell you to do - Do a system restore. On the phone to them the first thing they will tell you to do is to do a system restore (this is even if you've tested it with Linux and found it to be a hardware issue - btw if you did test it with Linux it's never a good idea to tell them as they may try and say you've invalidated your warranty by running another OS or some rubbish like that - even though a linux live CD does not touch any part of the PC it's just their way of getting out of paying out). When doing a system restore ensure you backup everything from your laptop you wish to keep - photo's, documents, files, mp3s everything you don't want to loose put it on an external drive, and then remove the external drive and put it somewhere safe. When doing the system restore do not have any removable drive plugged into the computer at all (USB drives, flash drives, memory sticks, etc), you probably wont erase them but it's not worth the risk. Then just run through a full system restore to restore back to factory settings (normally to get into this you will probably have to press F12 when the computer is booting up, or sometimes it can be F8 - it depends on the computer and the instructions on how to do this should be in the manual).
After doing a system restore you should then find Windows has cleaned up any software issues it may have had.
If it continues to have problems though try updating the drivers, and if your competent enough with technology see if there is a BIOS upgrade - nb you should only ever do a BIOS upgrade if you are confident enough with technology, plus when doing a BIOS upgrade ensure your laptop is running on mains power with a charged battery and during the upgrade DO NOT attempt to use the computer, or switch it off, or disconnect it from the mains at all. A BIOS upgrade is the most dangerous thing you can do to a laptop, but sometimes it is necessary, if it does go wrong it can render the laptop useless as the BIOS is a tiny piece of software that tells the PC exactly what to do next when it's first turned on, so without that software the laptop wont do anything which is why it is so risky to do.
If none of the above solves your problem contact the manufacturer and describe the fault to them and see if they can help.