i don't think so.. normally the setup asks whether to remove older versions.
but i think you can install both alongside each other but you'll be prompted to insert the cd of whichever version of office you use each time you use the other version.
example when you use 2000 and then open word xp you'll be asked to insert the office xp cd before it starts and then when you use access 2000 you'll be asked to insert office 2k cd. this happened once before on an older computer when i was trying out office xp.
hope that made sense :o)