Sure, you could do it...but you will get different results for different games. One of the problems that I had using a wireless g router was the intermittant disconnects. These disconnects were simply nanoseconds so they were not recognized by the router connection, but they were by the game itself. So, after a little bit, in Warcraft, I would get "You have been disconnected from the server" There are certain thing that you can tweak on the router to help this connection though. Problem is, the router "opens and closes" the wireless connection to see if it is still active. This is so fast and transparent, but some software running on the net is affected.
The speed wouldn't be a problem......depending on your machine, it can be just as fast as a wired connection. Reliability would be the only factor.
-Mike