Welcome to the wonderful world of inefficient code.
One of the ways we can solve the world's energy problems is to harness the power produced by all of the hot air that DocHillingswirth and SteveScrumpyUK generate.
Remember, it's NOT your soundcard, its the software.
You can get the software to work, (at least marginally,) by doing the following. You can even get results from an AC97.
1) install ASIO4ALL
2) defragment your hard drive.
3) never use the real time audio effects (apply them later.)
4) rename the aud.ini file and restart GT3 to regenerate the cakewalk settings.
5) update the VST program and rescan in the VSTs.
6) turn off your network card.
7) shut down all the unneeded windows services and other crap.
8) If you dare to live dangerously, turn off all of your virus and spy checkers while disconnected to the network, but make sure you turn them back on.
9) close all other programs.
10) don't use a USB drive for your cakewalk work files.
11) apply the latest GT3 patches.
By doing these simple things. you can run GT3 on just about ANY SOUNDCARD and yes even the famous AC97.
Some additional things are to not run on Vista which ain't supported. Downgrade from Vista to XP. Also, if you want to use real time effects, a line6 toneport or something similar, will do the trick. (However it will not fix the realtime monitor issues with latency.)