This is the best game ever made. Must be 10 years since I last played. Still own the War Chest edition. Where do I start? Will it work on Windows 7 and Windows 8.1? How do I get up and running on multiplayer?
There are also some X-null reborn patches and so on so you can browse the game servers www.x-null.net but sugest you start with the desktop tool above that works great
The links given above are excellent sites and tools to help you connect to servers
Unfortunately GameSpy shut down, and X-Fire will shut down friday so those tools are unavailable now.
To get back into the game, you can check out my guide which holds a lot of information about the game (not just about the game itself, but also about bugs, tools/software, fixes, settings, mods etc.).
It also contains information about playing under Windows 7 or up, if for some reason it shouldn't work!