Hi Sean,
I am pretty certain you can get an external firewire empty hdd case. If you buy a seagate drive, and maybe others, not oem, you get a 5 year warranty. Many pc motherboards have firewire built in. Since it seems it is a backup once and restore situation, then offline backup that you want, I think that even fw 400 would be fine. If it is not fast enough for the hdd you purchase, then you already have the disk, sell the case on ebay, (or keep it as a spare) then go the fw 800 route. afaik, 800 is backwards compatible with 400. If you buy an external unit, with a seagate drive put in it, then you only get the case maker's warranty. I think Seagate bought Maxtor, or maybe it was wd, about a year ago. At the time I was doing this, the fw 400 throughput was faster than the hdd capabilities. You may be able to save even more cash... ;-)
The NLE systems, were based on windows 2000, and were dedicated pc's just running the NLE software - Avid, and the like. (just before Avid got into bed with IBM).
Best wishes,
Ray