I'm thinking about going with SATA, only because of price. To purchase a server with SCSI is a more expensive option and cost 3 times the price.
What is the problem with SATA, is it really that bad
SATA is excellent, much faster than PATA and an equal of SCSI for most systems. SCSI may still have the edge on large, database intensive apps, but I would be surprised if you see any performance issues with SATA.
Avoid the cheap SATA "fakeraid" RAID cards. Either buy a decent one (e.g. Adaptec) which makes the disks appear as a single disk to Linux, or let Linux do software RAID. It does that well - faster and more robustly than many cheap SATA 'fakeraid" cards.
http://linuxmafia.com/faq/Hardware/sata.html
What about AMD's Dual Core Processor?? Not Daul Processors.
I haven't tried one, but it should work. Why don't you try one and report? It's almost certainly overkill for most server uses. Heavy (and I mean heavy) webmail use might make it worthwhile, but most modern CPUs have plenty of horsepower.
And a recommendation for Tape Backup, what brand does sme 7 like
Pretty much any SCSI tape should work "out of the box".
IDE tape drives may work, using ide-scsi emulation (see bug 788).
I haven't heard reports either way of SATA tape drives. They should work just like SCSI tape drives.
Floppy tape drives - just say no (I don't think they even work under the 2.6 kernel, but say no anyway).