I have to have dual operating systems, Windows XP & 2000.?

As others have mentioned, use seperate partitions for each OS. Install Windows 200 first and Windows XP second. That is very important.

the basic recommendation: 2 or more partitions ex. drives C:, D:,.. i presumed your drive C: is where Windows2000 was installed, so drive D: would be used for WindowsXP. to start, just boot normally on Windows2000 then insert WindowsXP installation cd (i presumed to be E:).. just follow the self-explanatory instructions that leads you to install the new OS on drive D:..

Yes, you can have both. But do not install xp on same drive on which you have win 2000, select another drive. You have install all programs that you use in wn 2000 on win xp again.