EDIT: I'm sorry, I saw Xtreme Sound in the title and assumed creative. I can't help you with that card (the Diamond), I never saw a good review on them so I wouldn't buy one. Good luck. read the rest of the post if you are thinking of buying a Creative Card though..........
Four words: Write your own drivers.
Nope, I'm not being a smart ass. Creative deliberately crippled their sound cards so they would not work correctly with Vista. In the words of VP for Corporate Communications Phil O'Shaughnessy to a regular poster on their forums, "Daniel K" who DID write drivers to make Creative cards work in a forum message that also threatened to sue "Daniel K": "By enabling our technology and IP to run on sound cards for which it was not originally offered or intended, you are in effect, stealing our goods," writes O'Shaughnessy at Creative's forums. He goes on fiurther in the message to state, "If we choose to develop and provide host-based processing features with certain sound cards and not others, that is a business decision that only we have the right to make."
You can no longer read the original post made on Mar 08, 2008 at the creative forums because after a few days someone realized that Mr. O'Shaughnessy had basically admitted that Creative deliberately sabotaged their own products so they would not work in Vista and they removed it and replaced it with a nonsensical press release. However you can find the original message
here among other places as it was a matter of public record and as such saved by many media outlets. The complete statement before being removed was as follows:
Daniel_K: We are aware that you have been assisting owners of our Creative sound cards for some time now, by providing unofficial driver packages for Vista that deliver more of the original functionality that was found in the equivalent XP packages for those sound cards. In principle we don't have a problem with you helping users in this way, so long as they understand that any driver packages you supply are not supported by Creative. Where we do have a problem is when technology and IP owned by Creative or other companies that Creative has licensed from, are made to run on other products for which they are not intended.
We took action to remove your thread because, like you, Creative and its technology partners think it is only fair to be compensated for goods and services. The difference in this case is that we own the rights to the materials that you are distributing. By enabling our technology and IP to run on sound cards for which it was not originally offered or intended, you are in effect, stealing our goods. When you solicit donations for providing packages like this, you are profiting from something that you do not own. If we choose to develop and provide host-based processing features with certain sound cards and not others, that is a business decision that only we have the right to make.
Although you say you have discontinued your practice of distributing unauthorized software packages for Creative sound cards we have seen evidence of them elsewhere along with donation requests from you. We also note in a recent post of yours on these forums, that you appear to be contemplating the release of further packages. To be clear, we are asking you to respect our legal rights in this matter and cease all further unauthorized distribution of our technology and IP. In addition we request that you observe our forum rules and respect our right to enforce those rules. If you are in any doubt as to what we would consider unacceptable then please request clarification through one of our forum moderators before posting.
Phil O'Shaughnessy
VP Corporate Communications
Creative Labs Inc.
You can read some of the functions Creative disabled and how Daniel fixed them :
here.
In short, while Creative has been forced kicking and screaming to enable some of the features that they deliberately disabled 5.1 sound is not one of them. If you just bought the sound card, return it and get your money back. Or you can use google to find drivers that DanielK wrote that will enable it sabotaged features. As I returned MY Xtreme sound card last April when this all came to light, I can not verify that Daniels driver work. I also can not verify that you can still find them. At one point, he stated he took his drivers off the net since they allowed people to buy Creative and have it work lol.