2 ?'s - Where can I get the smallest case that still has an AMD approved PS, and can I still download Linux?

[KDOG]

I have a spare ECS K7S5A mobo lyin' around and I'm thinking of making a DVD, internet box for the living room. So I'm looking for a small case that will still house a ATX mobo. Also, I sure ain't buying another copy of WinXP, so I'm wondering if I can still download the latest & greatest version of Linux and use that. Can I network a Linux box and WinXP box together? Oh, and what's a good cheap tv-out capable video card that looks good on the TV?