This is probably going to be a boring and pointless post.
I got a rack for all my computers (except my main quad-monitor one). So, I got my server plus 2 other computers & 3 monitors...add the router and switch on the rack (I also have another computer but with no case). Surprisingly, my server is running quite cool @ 26C (CPU) and 27C (Mobo).
I installed Fedora 9 'The Spin' version last night on an old Dell. Quite slow (only 128MB RAM in the system) so now I'm installing Easys, a Slackware based distro (Running KDE (which isn't old-computer friendly)).
Furthermore, I installed Xubuntu 8.04 (8.10 on the 30th!) on an old Thinkpad (which I love). I got it running pretty good, considering I was using Fluxbuntu 7.10 before.