This is guide is using OpenSuSE 11.2 and VirtualBox 3.2.2
You'll need the closed source version of VirtualBox because the OpenSourceEdition (OSE) doesn't support USB and other things we need for gaming.
Pretty much the same as on a real PC. I recommend Windows XP SP2 or SP3 as your guest system, but you can also use a newer variant, if you really wanted to.
Time to make a few changes. The Settings dialog of VirtualBox is pretty simple, so I try to make it brief. You'll need 3D Video, USB support and Bridged Networking. Bridge to the network interface you're using for the internet connection on your host system. The Bridge Mode is important because it allows us to assign an own IP adress to the Guest, which is important for all the port forwardings to keep working. So you'll end up with one computer with multiple Interfaces attached to the LAN, each with an own IP.
Note: It should also be possible to play online using NAT as the virtual network adaptor, but you would have to create another instance of port forwardings from your host OS to your guest OS.
Install all the software you need to play online. Voobly and maybe Errant Venture, the games, and don't forget the Guest Additions. Just click on Devices → Install Guest Additions (Host+D). It will mount an .iso file in your Guest System. They contain video drivers for 3D and more useful software.
Just right-click on the USB icon in the status bar and select the Joystick. All the devices you select there will get passed through directly into your VM.
Compatibility Mode As always, run the games in Compatibility Mode. Just change the Properties of zxvt__.exe. Disable 3D Hardware If 3D Hardware (in game options) locks up your game, try to disable it! However, keep the VirtualBox 3D Display enabled, this is obligatory. Sound should work out of the box. Setup Display VirtualBox cannot “stretch” the video output from the legacy VGA resolution that XvT is using to a modern High-Resolution. In other words, VirtualBox can't change the host's display resolution. So I worked around this by changing down the host resolution by myself. You'll have to play around with these settings. 800×600 worked quite well for me.
Thoroughly test the game offline before you seek online bloodshed. Also, the Port Check utility could come in handy. Good luck & Happy Hunting!
XvT can also be played on Mac OS X! This setup has been tested running Windows 7 on Mac OS X (10.5.8 [Leopard]) using VMWare Fusion 3.1.0. VMWare Fusion only runs on x86 Processors, so older Mac Hardware using the PowerPC architecture are not supported.
VMWare is shareware but has more features than VirtualBox. I can't give you any advice on how to solve the shareware problem. You are on your own.
This should not be too difficult from the VirtualBox settings. You'll need bridged networking again.
Under the “Settings…” menu for your particular virtual machine, you go to “Network”. Select “Connect directly to the physical network (Bridged)” and select the device through which you will do this (either your wireless router or ethernet).
Turn on the virtual machine and connect to the internet as you normally would. The virtual machine should have its own IP address now.
VMWare Fusion doesn't support 3D accelleration, but it should work without it. Needless to say, the game won't run with “3D Hardware” enabled in-game.