My WD1200JB is pretty much silent, feels just as fast as my dad's Maxtor Atlas 10k-III (a 10,000 RPM SCSI drive), and has 120 gigs of storage. It also runs very cool - MUCH cooler than my old SCSI drive (a WD 10,000 rpm SCSI drive...) which sounded like someone was blending frozen strawberries during seeks. So far, I'm very satisfied with the drive for the most part; I really have nothing negative to say about it.
Personally my opinion is that SCSI is a big, big waste of $$$ for the vast majority of people out there. Don't buy into the hype, cause that's all it is.