+1 For Ubuntu 7.10, its a great operating system - a lot less problems than trying to maintain a windows box. Freespire is okay I guess but I think that the CNR technology is much more likely a low quality version of apt-get with a fancy frontend.
Whatever distro you get, try to get one that is debian based. This would thereby allow you to access the hundreds of deb files out there. (Debian probably has more packages than any other distribution).
Furthermore, Ubuntu 7.10 sports an updated kernel which means that there is less polling of your CPU and as such a resulting save in power requirements.
Its quite a learning curve but its very much enjoyable too. If you are just starting out check out the Ubuntu Forums at
Code:
http://www.ubuntuforums.org
, its very helpful. Also, google for the ubuntu guide, its a website with plenty of tips and tricks to get you started with multimedia applications and samba (windows networking) deployment.
Oh, and have a look at deluge, its a wonder torrent application if you favor Bittorrent technology for file transfer.