Hey there are all kinds of topics that are not even on the issue of technology on this site, so I wish more folks would talk "gaming" or "gaming tech" more often.
I have used wireless before to connect to an play games online, never had a problem with speed or reliability at all...I would suggest just use good wireless network common sense --- make sure not a lot of interference causing devices in the general gaming area (wireless phones, microwaves, radios, etc.), don't try to go through too large or too many walls/ceilings/floors...keep your distances as tight as can be practical for comfort level of you and your gaming buds, etc.
I'd suggest making sure you enable the highest bit level of WEP and manually assign the keys to each person on your wlan, to maintain some kind of privacy of your network (and to keep folks from hijacking your network connection and sapping your bandwidth).
Also go with the g standard so you get 54mbps (which in reality is no where near that high, but its still much better than just 11mbps).
I think you'll be fine.
PS. Did you play HL 2 yet? Definitely destined to be one of those games people will refer to as a "Classic".