Here's what I found to work for me with the Audigy Platinum II EX.
1.) Download and install the XP drivers -- DO NOT RESTART. You may notice that you have sound already. Don't bother to try to use the Audio Console or other sound utilities -- they may hang or crash the system or drivers.
2.) Without rebooting, install the latest Soundblaster drivers (Beta for Vista) from Creative. Reboot this time.
3.) When the machine restarts, don't be in a hurry. It appears that Vista is busy updating protected storage and swapping out drivers. This took about 20 minutes on my 3.2 GHz hyperthreaded processor. Go ahead and do something else while it's cooking.
4.) When things settle down (processor activity slows and disk activity slows) open the Audio Console (Creative) and adjust the settings for 5.1, 6.1, or stereo to match your system.
Bingo!!!
The moral of the story is that the Creative Beta install is expecting some evidence of the sound card before it will replace the drivers and that Vista takes a long time to establish all the drivers for the AV links after Creative Install completes. Hope this works for you. I spent 3 days on it.
