ghostrider,
going back a ways.
initially I would do a File\Run\SFC /scannow to restore any missing windows files. You'll need your Windows 2000 CD for this.
that may help the slowness, if not time to remove temporary files, do a checkdisk and a defrag. also remove unnecessary stuff from your Startup.
You can also find msconfig.exe by searching Google and downloading from a reputable site or copy it from an XP computer. Run the command msconfig and use it to remove any unneccessary programs from the Startup TAB, then click on the "Services" tab and check the box "Hide all Microsoft Services" and then uncheck any unnecessary programs there.
Or it may be time for a format and re-install. i never used W2k, but even with XP doing an occassional format and re-install is necessary from time to time, as was W98.