|I missed this one before but will respond now.|
I used to be part of a group of gamers who all pitched in and bought our own gaming server. After a couple of years of actively being a member of this group, and being a server and game admin for them, my interest in gaming constantly waned and I left the group about a year ago.
The group and their server are still active today.
If you're contemplating hosting your server at your home I wouldn't bother. I doubt your bandwidth would be sufficient for more than just a couple of users connected and gaming at a time.
We had our server hosted at a 'colocation' site in the US with a guaranteed 1.5 Mbps bandwidth and a "burst rate" up to 2 Mbps.
You might be thinking, "I have a bigger pipe at home" and you'd be sort of right, but mostly wrong. Enterprise level bandwidth is NOT the same thing as highspeed internet you get at home. Our gaming server ran two different games. It ran 4 instances of one and 2 of the other simultaneously and had usually 20 to 30 people per server connected at all times. That's a total aggregate of 120 to 180 simultaneous connections.
If you tried that at home, it would stuff your internet connection up and nobody would be able to do anything.
We ran 2003 Server as our OS. You don't need to run VMware or anything like that. Most games that are multiplayer have two ways to install or play, host (server) or client. When installing on the server, we installed in "Host" or "server" mode.
The colocation site who hosts the server provided us a block of routable IP's to use. If I remember correctly, we had a block of 10. While you probably could use a firewall and NAT with port forwards setup for different ports to run your games, it's a whole lot easier to setup and maintain if you do it with routable IP's.
There's a ton of information on the web that's been written by people with experience doing this. I would search for info pertaining to the particular games you wish to run. Do some tests at home and once you've got it all figured out, if you wish to have an active server with lots of games and client connections, I would then start looking into colocation sites.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.