Help setting up a server. Options

[heyo-captain-jac...]

So I've got this old PC, so old it came with Windows 2000. It currently has XP service pack 1 installed, but can barely run it. Right now it runs on my unused Mandriva Live CD, and performance is still pretty crappy on that.

So I figured, why not turn it into a server? It's got a 90gb hard drive, and a half gig of RAM. The processor is where it lacks performance. It's a single 1.3 GHZ Pentium 4.

I would like to find out:
1) What's the best light operating system to run a server on? (Be more descriptive than "Linux")
2) How could I maximize performance?


Also, is there anything else I would need to know?

Edit:

User interface makes no difference, I've used nearly all of them. As long as I'm not running on some GUIless software like MS-DOS, I'm happy.