I would suggest Ubuntu Server 8.04 LTS edition, the 8.10 has had a few problems being reported currently.
Ubuntu server does not come with a graphical user interface, and ideally, don't install one it slows you down.
Suggestion is using Webmin, and SSH via something like Putty, you are able to do everything you need to do nicely. Webmin also comes with a java file manager, so you can get a graphical file management tool that you can use from any computer via webbrowser (with ports open you can even use via the internet, it comes with encription)
(Ps whats the rules on posting links to things like ubuntu/putty/webmin?)
Feel free to drop me a message if you want help with a ubuntu server.