Heyo Daniel_72
There's nothing to making a dedicated server machine as of special hardware/software. Of course you need Hardware that's powerful enough to do whatever you want and the corresponding software to make the servers run.
If you'd like to, just keep your current OS on there and install whatever game server you'd like. You'll have to make sure you have a static IP on that machine though if people over the internet will need to connect.
Cheers