Windows 2000 Professional is an excellent operating system for the above average user.
Pretty much all the abilities added to WinME are there if you bother to look for them.
Win2k is rock solid. I have one machine that has never been rebooted since it was installed months ago. If something hangs up you just kill the process and Win2k is back to normal.
I will say this:
Research all of your components for compatibility with Windows 2000. Some 3rd tier component manufacturers never bothered to update drivers for Win2k, even some reasonably good brands. If there aren't explicit Win2k drivers for your hardware, replace it before installing.
For hardcore FPS gaming a tweaked Win98SE installation will probably serve you better. Drivers for Win9x are more mature and faster. Personally I run mainly Win2k on all my rigs with a couple of Win98SE and 1 WinME. The WinME was simply for an experiment. I am generally happy with it, but I am still not sure why I spent the $50. Installing the latest Windows Media Player seems to give most of the same multimedia features, and Win98SE was already pretty good about networking.
If you have a home LAN even Win2k professional gives you features that are great to have, BuiltIn WWW, FTP, SMTP, the ability to route any Internet connection to the local LAN *EASILY*
If you are truly a speedfreak use 98Lite the custom windows installation on your gaming rig. You'll see gains of 10-15% more overall performance.
My $1.25 like it or not.