You sure that's the site? I tried and every piece of music I tried to download came back with "404, the file you requested does not exist".
NM
Anyway, I poked around the web and found, much to my horror that
www.sshock2.com (official system shock 2 fan page, or some such) had
pulled all its musis files. But I did find another site:
www.geocities.com/soldier34927/