Henery,
You seem to be the one looking to buy here -- I have the Audigy in my K7D, and have tried it in both the 33 and 66MHz slots now. It works fine with each one. If it matters, I'm running (2) 1600 XPs modded to MPs on the machine. Other cards are a Radeon 8500, an SI RAID card, Analog video editing board. So far no complaints with the Audigy in this setup. Very decent sound quality. If you want to fork out the cash for the best, the Audigy is good, but there are other professional (Terretec, etc.) cards that are better for music creation. I just couldn't justify the $ for them.
Hope this helps,
Jed