My home network is on a wireless Linksys, my mom'ss computer, across the wall from mine, seems to work fine, it will get 94% conncetion, but my dad's is on the opposite side of the house, and usually connects around 47%, he complains its not much faster than dial-up.
So maybe moving closer to the router, if possible, will help. (Which, I know defeats most of the purpose of it being Wireless, but hey, no more drilling holes in the ceiling.)
Hersh