I recently wrote an article about how to buy laptops, so the following should help you out.
Some of the things you need to consider when buying a laptop include:
One of the first things you need to consider in a laptop is the CPU. The latest laptop CPUs include Intel's Core Duo and Core 2 Duo processors which outperform older single-core Intel processors (e.g. Pentium M). Other laptops use the AMD Athlon Turion 64 X2 dual-core processor - which is also a good performer. In general, however, if you're looking for a laptop, I'd advise you to look for one with an Intel Core Duo processor. You can also read this guide to find out more.
2. System memory
The amount of RAM in the laptop is very important. If you're not short of cash, my advice is to get at least 1GB of RAM - that is the minimum you need to get newer PC applications to run fast. Also remember that you can always add more memory to your existing laptop. You may be interested in this short guide on how to install new memory modules into a laptop.
3. Graphics memory
Laptop graphics are another feature you will want to consider. Typically, I'd say you should go for 128MB of dedicated video RAM. Also, ensure that the graphics memory is used solely for graphics use and not shared with the main memory. If you intend to play games on the laptop, then look for advanced 3D graphics chips with about 256MB to 512MB of dedicated graphics memory. Be prepared to fork out a lot more cash though.
You will also want to take a look at the laptop screen. Laptop screens have recently become bigger. Most of them have gone widescreen so you can watch movies or edit spreadsheets more comfortably.
If you intend to use the laptop from home a lot, then I'd go for a 17-inch wide screen. If you are more concerned about portability or if you travel a lot, then laptops with screen sizes of 12.1 or 13.3 inches might suit you better. There are also 14.1- or 15-inch screens for laptops, but I believe manufacturers are shifting away from these models.
Here's another critical factor - laptop battery life. I personally find it very frustrating to have my notebook power run out after 15 minutes at Starbucks. What you need to do is to buy a laptop that has about 3.5 hours of battery life, running on a Core Duo or Core 2 Duo processor. Make sure you question the retailer on how long the battery can last - a short battery life is usually a deal breaker for me.
6. Keyboard and Pointing Device
Some people believe that the keyboard and pointing device on a laptop is important. If you have big fingers, you might be more comfortable typing on a larger notebook keyboard than a small one. Make sure you try the laptop out - get the feel of typing and navigation before you buy the laptop.
7. Optical drives
I'd usually recommend getting a laptop with a rewritable DVD drive as a minimum. One thing you need to know is that some laptops sacrifice a DVD drive in exchange for a lighter weight and portability. If you don't think you need a DVD drive all the time, then you might want to get a model that doesn't have one.
8. Hard drive
In the laptop hard drive department, what can I say? More is better. These days, you can get a notebook hard drives coming in sizes of 160GB or more. You can also get SATA hard drives if you have more cash.
Another thing to note is the weight of the laptop. Now, when you buy a laptop, always remember that the total weight includes the notebook AND the AC adapter, any external modules, and their cables. These can add up to quite a bit of weight.
These days, you will find that most laptops come with at least two USB 2.0 ports - I'd recommend that as a minimum. If you do a lot of video editing, then a FireWire (IEEE 1394) port also becomes essential.
You should also check for good network capabilities. Make sure your new laptop has built-in ethernet capability, a built-in wireless connection and also built-in Bluetooth (if you need to transfer data between your mobile phone and the laptop).
Some of the laptops also include card slots for removable media such as CompactFlash, Secure Digital and MultiMediaCard. If you take a lot of digital photos, then this feature might matter to you.
Hope this helps you out.