My computer spec is:
Intel quad core @2.40 GHz,
4gb Ram,
NVIDIA Geforce 8800 GT 2gb.

I am with wanadoo/orange BROADBAND using a 802.11 USB 2.0 adaptor (Inventel), i dont know if that MEANS anything to anyone.

PROBLEM: The wireless internet connection runs smoothly with no PROBLEMS whilst browsing websites and downloading files, however whilst playing an online game (for example: counterstrike source) my internet suffers from sudden 'bursts of lag' roughly once every 60 seconds. These lag bursts cause the game to freeze momentarily (roughly 2 seconds, never more, never less). Apart from these lag bursts online GAMES run very smoothly with no problems whatsoever.

any help appreciated, thanks!

JoeTemporarily disable your A/V apps...
Shut down any unneccessary running apps in the Tray.

See if things improve.I just tried and still no luck

My old computer I had inventel/wanadoo software installed and was ok, maybe the drivers for the adaptor isnt installed?!
I would install the wanadoo software however I seem to be having a problem on Vista.

Thanks. Joe.