Server Hosting

I'm in the process of building a dedicated server out of old pc parts for my family and friends to use for storage, music and picture transfer, backup, minecraft, etc. I have a 40dn 10up connection and a 2tb drive so I should be fine on space and speed for now.

I'm a beginner at server hosting so any input will help.

The specs are

AMD 1.8ghz p-o-s
512 RAM soon to be upgraded to 2gb
40dn 10up
120gb drive running just Windows Server 2008
2tb external for storage

Ive got the remote connection working so I can ditch the monitor and keyboard. Minecraft server up and running. I'm working on the teamspeak server and ftp server.

Any and I mean any input is appreciated. I'm putting this together by the seat of my pants and am worried that I'm missing security issues and other aspects that I don't know about. I'm trying to learn Ubuntu Server so I can eventually switch to that software but it's all command line and I've never used Linux before so it'll take awhile to learn.