I've got the X-FI gamer & the T20's.
The T20's are canny, they actually fill a room better than when you sit in front of them. I think this is to do with the vertical bass firing ports, the bass doesn't get to those sitting directly in front of them, but plenty everywhere else.
Therefore i couldn't highly recommend them for desktop speakers, however i could possibly be spoilt with my AV setup and previously a Cambridge Audio Soundworks by Creative.