We'll assume you're doing a CLEAN INSTALL (not an upgrade)
If possible, boot the computer from the Windows 2000 CD. You should see a message "Attempting to boot from CD... Press any key to boot from CD..."
When done this way, Windows 2000 setup should take right off. If that doesn't work:
1) Get into DOS (not a DOS prompt under Windows, boot with a Windows 98 startup disk.
2) Change to the CD Drive (type X: <press enter> where "X" is the letter of your CD Drive)
3) Change to the i386 Directory (type cd i386 <press enter>)
You should now see the DOS Prompt: X:\i386>
4) Execute setup (type winnt <press enter>)
Setup should initiate
Reminder: This performs a clean install, flushing your drive clean.