I don't think it makes much difference which soundcard you get for gaming.
If you have average speakers you won't hear the few decibel difference in better signal-to-noise ratio cards.
I don't know the real difference between EAX 2.0 and 4.0, all current sound chips support EAX 2.0, and not many games have 3.0 / 4.0 support anyhow.
In games there are a couple of frames per second differences between "inexpensive" sound chips and the expensive ones, so not that significant either.
I chose my soundcard because of its connectors - it supports multichannel audio in all applications via digital out connector.