I too use SATA drives for back up now and there are a PLETHORA of options -- USB, Firewire and at least three separate SATA connection options; with and without RAID; 1, 2, 4, 5 or even 8 drive bay configurations.
Knock yourself out on the research HERE
and let us know what you decide!
FWIW if you want an external RAID solution:
Buffalo has their NAS 10/100/1000 and USB2 in a 1TB configuration and is currently selling for about $650 -- though it uses 4@250G IDE drives. (This gives you 750G of usable storage in RAID 5 configuaration.) However, WiebeTech has a 5-bay SATA 1.25 TB RAID solution complete with 5@250 SATA drives (1 full TB of usable R5 storage) that can be had for about $1700 if you shop. Obviously, at these prices the IDE Buffalo NAS is pretty cheap
IF we do the math... Bare drives are selling for about 35 cents per Gig on 250G and smaller drives (IDE or SATA). 500G drives are about 50 cents per Gig. To get redundant back-up in a non-RAID configuration, you need to double these figures. IMO, this makes the 1 TB Buffalo a pretty good buy since it includes RAID, a box and USB or Network connectivity for 87 cents per RAID-ed Gig. Just a thought...