There are a few problems with wireless adapters for fast paced gaming. for example,
1. The current specifications of WiFi (unless it has changed again) for example mean that all adapters have to wait in turn to broadcast. This adds lag.
2.You cannot controll which broadcast channel your neighbours are on and this increases lag and reduces bandwidth.
3. Lag in games = bad.
The best possible wireless adapter for gaming will not use a common standard. Therfore it would be a different wireless technology. Most current wireless adapters just won't make a noticeable difference. Only thing they can change is broadcast strenght.