With my K7M I run one WD and one Maxtor. Both are ATA66, 7200 rpm. The Max is very quiet but the WD isn't really noisey. They both bench about the same on HD Tach. Since ATA66 is not fully utilized I don't see much point in buying into ATA100 yet. There are better, more expensive drives but with the no-hassle warranty and ease of installation I am happy.