If you are into tech stuff, I second everyone else's opinion for getting some WRT54Gs.
As Lasereth mentioned - I have 2 WRT54Gs in which I purchased for $22 each when they went on sale.
I flashed both with DD-WRT and now my entire house has literally 100% signal in every single room. I have one router upstairs, one router downstairs. And the best part? Both routers support hardware connections. In other words, both routers can have devices plugged into them (like an Xbox 360) and also transmit wirelessly - without being connected to each other physically.
My WRT54G upstairs is connected to the internet and my main PC. My WRT54G downstairs is connected to the Xbox 360 and nothing else, but the 360 has Internet