I just solved the problem with adding a test cert to IIS in XP. I kept getting keyset not available errors. Also, this was in my event log:

A fatal error occurred when attempting to access the SSL server credential private key. The error code returned from the cryptographic module is 0x80090016.

I finally solved this with the following KB article from MS:

System Errors When You Open World Wide Publishing Service or Administrative Tools Services

I know the title looks deceiving, but it did the trick. Has to do with folder permissions. The prob is if I had read this, then I never would have had to enable Certificate Services and IIS oon my win2k3 box.