I am pretty sure it is possible...the only issue will be that 2000's bootloader will override your current one...meaning 7 and Vista might not be detected and added to the loader when done installing...if that happens pop in your 7 Disc and choose to repair startup problems
Oops! i created a third unformatted partition from disk management and chose to install 2000 there (from BIOS) but it told me that Drive C must be formatted. I thought that this affects the whole drive so I cancelled installation. What should I do? Why does it tell me that even though I choose a specific partition?