I think it's going to be a bit over $100 (although the prices are going down all the time), but we set up a wireless network with a PC and laptop with a Microsoft kit and it has worked extremely well.
Here's a link to the product on Amazon but it looks like they don't carry it anymore. There are some people selling new kits on there.
http://www.amazon.com/exec/obidos/tg...onics&n=507846
You would need to buy that kit and two cards for your PC. We got a USB one but you can use any kind.
Our wireless network is INCREDIBLE. I have a three story house and I get a great signal on every floor in every room. Read the reviews for that router...it's a great one.