Late opinions of questionable merit:

1) In 2008, unless you *must* do it to provide a transparent disk volume over 1TB to lots of people, I think any sort of parity-based RAID like RAID-5 is a bad idea. It only increases risk of heartbreak (unless of course you have nightly rsync and you really are not concerned about loss of your RAID5 disk system.)

2) With affordable single disks now going to 1TB and beyond, I would say RAID-1 -- simple mirroring -- is the way to go if you can...

3) Some mobos come with up to 6 SATA ports. They could support up to 3 disk mirrors in software RAID,

4) With simple RAID1 on a multiport mobo, you could "leapfrog" -- set up system on ports 0-1 mirror and data/var on ports 2-3 mirror, then copy /var to new mirror on ports 4-5 when new 2TB disks drop below $300 CAD each. All in software RAID off of a cheap commodity mobo without any driver considerations for the various low-budget RAID chipsets on different mobos.

5) We use OpenFiler at work for a backup rsync server. It was a cinch to set up -- took like 30 minutes. Yay!

6) While hardware RAID benefit may be debatable, a 3Ware card let us have 16 SATA ports in a single box (so we can "leapfrog" quite easily). Hard to find a cheap mobo with 12-16 SATA ports.

7) Some of the cheaper hardware RAID cards like the 3Ware 8006-2LP mark the disks such that the disks are completely unusable unless they are attached to that specific controller.

8) When I had some problems with a workstation that had a RAID-1 on a 3Ware 9550SX-type controller, I was pleased to discover that 1 of the Mirrored disks could boot just fine when attached to a simple SATA port on the MOBO.

So, hard to tell what might happen with some of these controllers without testing aforehand, but testing worthwhile.

I will only do parity RAID now if it is in a high-end system/NAS that gets nightly backup.