The thing is that it's mostly used for downloads and as an emergency backup, but it's now a bit long in the tooth for the backup part since a LOT of the software I use now won't run on Windows 98 anyway. It really needs to be an XP box for maximum compatibility, although at a pinch I can do without OCR, Pagemaker, and the other applications I own that demand XP for a few days if I have to, so Linux or a Mac isn't absolutely out of the question. I want to avoid XP Media Edition crappiness.
As I've previously mentioned I've been thinking that it would be a good idea to have a PC permanently attached to the TV in another room, and if I use WiFi or extend the network in there, the backup PC might as well be in there. So what I think I need is suggestions on buying or building a small-case PC; I have two hard disks and a DVD writer in the current machine which ought to be OK for a new one, but memory etc. and the OS would have to be bought new.
If I go the Linux route which is the best implementation for a complete beginner with lots of Windows and some OS-X familiarity? The main applications I'd want to run would be bittorrent, a web browser (opera for preference), and Open Office, scanning and paint software, etc.
If I do end up with XP, what's the best deal at present?
Finally, what make of casing, motherboard, etc. should I look out for if I do build my own?