I bought an external HD for important file backup along with DVD Rs.
Granted if my C: drive goes I'm SOL, but I'd have to redo my entire system to do RAID 1. I have 2 DVD drives (one reader, one writer thanks to game CPs hating my writer) and 2 HDs split in half for 4 logical drives. I'm still running IDE, BTW, so I'd have to put ALL my 4 logical drives onto a single (much larger of course) physical drive. I think my 2 are a 160 and a 300? So I'd need a pair of 500s minimum.
Anyway, I've decided I'm going to build a new PC for Vista instead of upgrade the XP one so I'll have it around for backwards compatability. I don't want to mess with dual-booting! I'll probably start off with RAID on that one.