Many users are seeing this as a lack of support for the gaming cards they just recently purchased for advanced audio (some as high as $300 MSRP for the elite edition). currently the only X-Fi card that has a finished driver is the Xtreme Audio Edition which it turns out doesn't even use the same chipset as the rest of the X-Fi line but instead is closer to the Audigy SE card.Because of this lack of support, many customers are hounding the developers and support forums looking for answers to fix their problems. Some as simple as getting 5.1 sound to work to as far as the card not even being detected by the drivers that creative is supplying.
On a slightly positive note, Creative has developed a solution to the issue of MS completely removing the DirectSound HAL from Vista. Creative has released a program called ALchemy (yes the AL are supposed to be capitalized) which is designed to "transmute" the DirectSound programming calls into native OpenAL calls that by their nature access the sound card directly and completely bypassing the audio stack of the Operating system, helping to regain access to EAX and full hardware acceleration.
Until the driver issues are resolved, I would highly recommend anyone with a NEED to have their high end sound cards and other hardware to be supported under vista to not upgrade to Vista. If you still want to tinker with it, make sure you set up a dual boot situation then so you can dump back to XP for full hardware support. For those that are bold enough to not wait for the drivers to come out, the audio stack in Vista has been redesigned to support much better quality independent of what audio chipset you are using, which leads normal onboard audio to actually sound better under Vista than XP."