I'd recommend you get replacement antennas for the router and PC.
You might consider adding this booster to the mix, seeing as it's a good deal right now, and may solve your problem.
I have DSL coming into my dads office which is on one side of the house. My room is a good 100-150 ft range away from his office, and I am getting very poor range. There are also many walls between his office and my room.
I currently have a D-Link DI-514 (802.11b) and am wondering if I should maybe change to a different Wireless router. I also dont think I have the technology to get a wireless repeater.
Can anyone offer some suggestions on a good pairing so I can get good range on my internet for my house?