I have one and its great, but don't expect it to provide any accelleration with
GP2, because GP2 does not support any special 3D-chip.
The retail version of the Stealth 3D comes with a special version of Descent II
to show the capabilities of the card. I must say its awesome.
For more info, take a look at the following sites:
http://www.racesimcentral.net/ (for the S3 Virge and S3 Virge/VX chip)
http://www.racesimcentral.net/ (a site with info on virtually all 3D cards)