OT: New PC! Sorta...

[dogscoff]

If you're in the states and don't have a moral objection to shopping at walmart, they are (apparently) currently selling some decent Linux PCs for about $200. The stores are sold out, but I believe you can still get them mail order. They ship with a modified Ubuntu, but you can put whatever OS you like on there (well, maybe not Vista) and that would leave you plenty of cash to upgrade the storage. No idea if they support RAID.

Alternatively, pick up an old PC second-hand box from somewhere. A PC a few years old will serve your purposes well enough, and there are tons of perfectly good PCs out there that people think are worthless because of malware/ windows rot/ OMGIt'sNotBrandNew! - find one of these for sale, check that the mobo has the features you need, haggle, buy, reformat and off you go! $1200 should be more than enough.

Old laptops can be good as servers too, because they are deigned to be power-efficient, they come with a built-in UPS, and they are often very cheap on ebay because the screen or hinge or case or keyboard is broken. This doesn't matter for a server; just plug in an external monitor/ keyboard when setting it up and then administer it remotely from there on in. Not quite as expandable as a desktop, obviously, but a couple of USB hard drives might do what you need. Search ebay for "laptop spares repair"

One more option is a dedicated NAS solution, something like the Linksys SLU2. This is probably less hassle than setting up and maintinaing an entire PC, but less fun, less of a learning experience and probably less flexible.