I run a linksys etherfast wireless AP + cable / DSL Router (BEFW11S4) across the street in another house and have a Wireless USB Network Adapter (WUSB11) on my PC, both are 802.11b. The USB Adapter allowed me to move it around to find the best recption, the distance is about 150 Ft. this goes through 1 wall and the USB adapter is velcroed inside the front window of my house, I get Pretty good recption, Link Quality is almost always 70% or better and signal strength is 30 - 75 . Of course this depends on how many cars are in the line of sight from one to the other. I have seen times that I could get NO signal, but if I get a few cars moved, I will always get a good signal. From what i'v read going from a basement to the 2nd floor does not always work so well, The thing to do is buy the stuff and try it, you may have to move things around to get a better signal, but if it works, most of the time I would say it works very well (for me anyway), if you cant get it to work for you, just take it back. I spent about $235.00 US and I really cannot complain. And Yes you can access the internet with, uh.. I think about 32 pcs at the same time.( if you got a big pipe and/or a lot of patience.)
Try it, You just might like it.
Jim