Rich,
Undertoad is 100% right. You don't want to get a proprietary all in one solution that handles your RAID.
Get yourself a decent external SATA HD and case, and with the money you save, get a good backup program like Symantec Backup Exec desktop edition. If you want more backups, get more drives. Symantec will handle that for you, and their solution works.
If you don't want to spend the money, get yourself Robocopy GUI (which is so much more powerful than standard file copy that to say it is like file copying is an insult. I know, I use it at a customer site), or get DeltaCopy for Windows (which is a nice installer for Rsync and Cygwin).
If you still want a decent solution, get yourself a PC with a dedicated RAID 5 card (or onboard RAID 5, or Linux with LVM) and run your stuff off of that. You can get free iSCSI Initiator and Target software (Microsoft supplies the Initiator SW for Windows, and you can get Linux target SW at:
http://iscsitarget.sourceforge.net/), especially if you run Linux, and Gig-E ethernet cards are cheap.
This is something you want to think about
.
Thanks,
Mitch