Thanks Dale_B and others above for their imput. Especially glad to hear that it works fine with ATA 133 drives as I just purchased 6 Maxtor 200GB drives at $129 each from CompUSA and hoped that I could use a couple in a RAID configuration on a new 64 bit processor with a SATA C drive. Want to use XPPro so I can network with my other machines which still perform well for other less demanding tasks. BTW- what about CompUSA selling me a pre-installed XP PRO, is that something I shouldn't do? Buy an upgrade instead?