(OT) Should I get a Linux box?

[willdooUK]

Howdy - this is perhaps a little OT for a Perlmonks node, but I think you guys can probably help.

I've just gotten ADSL at home, but I don't have a router or modem yet. I was going to just get something standard, but it occurs to me I could go techy and set up a wireless LAN at home. I've got three things to connect - PC, XBox and a Pocket PC - and my flat's pretty small so I don't think I'd have problems connecting from the other room.
I could do with learning a bit more about networks and so-on, and I was thinking I could buy an old PC, run Linux on it, and use it as the basis for a home LAN. Maybe I'd even run it as a web- or file-server (perhaps even run a Shoutcast station).

Are there any flaws to this plan? Specifically:
1) Would I be crazy to run a server from my house? Anyone else here do it?
2) Would I need a separate firewall, or could I use a software one running on Linux?
3) My box at work will soon have a fixed IP address - would that mean I could securely connect to the box at home?
4) There are plenty of sub-100 pound PC's in Loot around the 300Mhz mark - is that a suitable box?

Basically, what should I watch out for?

I hope it's cool to ask for advice in this detail - I'm kindof a dunce when it comes to networking.

update (broquaint): title change (was Should I get a Linux box?)