For what you will proably do with that server, your specs are fine. My server is a P3 600MHz I found, 128MB SDRAM, and a 320GB IDE hdd I wasnt using. I use it as a FTP/HTTP server, and I am in the process of setting it up to handle all my downloads.
I have a wifi card in the server, I have it set to log in, and connect to the network by itself, then I manage it with Remote Desktop, so no keyboard, mouse, monitor... just sits in a closet with a power cord.
I always make sure it is ready to be used as a back-up PC in the event my primary rig dies, that way I can email, and research ways to fix the problem.