exmerge in exchange 5.5 and 2000

We are moving to a windows 2000 network. We will be moving to a new domain and replacing our domain controllers and exchange server. In our test network I have been unable to get the new and the old to see each other to establish a trust and move exchange that way, so we have decided to go with a fresh install of exchange 2000 and use the exmerge utility to move to the new server. I know the 2000 version is on the exchange cd. Can I use this also for the 5.5 version or do I need to get a 5.5 version from somewhere else? If so, where? Thanks a ton!