Wireless Internet Problems.

Hi,
In short, i have recently changed to wireless internet because my LAN connection stopped working for some unknown reason. Once i changed to wireless everything has been running smoothly until i have commenced paying games during the holidays. Whenever i seem to play games like Counter-Strike: Source, i seem to loose connection for around 4 seconds then reconnect.
Why is this, how can it be solved, and at what cost?

Cheers,
Sam