Can anyone recommend a nice light weight version/distro of linux (with GUI) that I could use for an HTPC? EDIT: Would anyone recommend any non-*nix OS?
geexbox is perfect if all you need is playback otherwise debian and fluxbox. Or if your really going for it mythbuntu
You could try XBMC live, a usb bootable version of Xbox Media Center for the PC. You can also install it onto hard drive as well. It's also currently only beta 2 but is probably due to go gold before christmas. More info here http://xbmc.org/forum/
Depends what your using it on, A 5 year old computer doesn't exactly need much support. What do you mean by the libraries? noob question.
The stuff that tells it how to work with uPnP and DLNA server. uShare is based on the same libraries but even though the PS3 is uPnP compliant it won't read the files.