Help me pick out hardware for RAID 5 fileserver!

First of all, a question about hard drives. A couple of months ago, I bought a Seagate Barracuda from frys. Model No. ST3500641AS. that is a 7200.9, would it be possible to raid with a 7200.10 or does it need to be EXACTLY the same drive? Also, I have an old HP sitting around. If I put a new motherboard with SATA capabilities, would I be good to go? It's about a P3 1.5 Ghz(don't quote me) with 384 Mb of RAM. If that would be possible, could someone point me towards the cheapest one that would work for this application? Thanks.

Probably would have been better to use the T-T-T-ech Yourself forum. And Dmorris probably has all the answers you need plus more.

Secretly.. I Wish I could be Dmorris

Moved to appropriate forum...

No, you don't have to match exact models or even brands of HDD's for a RAID array. For that matter, you don't even have to match sizes -- if you mix a 400GB and a 500GB drive in a RAID0 stripe, for example, the extra 100GB on the larger drive will be wasted and you'll have a 800GB array.

That said, it has always been recommended to get the drives as similar as possible, so as to avoid wasting extra space from larger drives, weird timing issues due to one drive perhaps being faster than another, etc. It's a rule of thumb but it isn't set in stone.

If you get a mobo with built-in RAID support you should be fine -- most with RAID-capable controllers will do RAID5, just confirm that before you buy it. Then you need 3 drives minimum for a RAID5 configuration. I'd be careful about the case though -- most HP cases are compact and cramped, and might not support the extra drives. Or might not cool properly if stuffed to the gills with drives.