NT4 to Window 2000 migration

I have recently acquired the responsiblity of net admin for a small company. I have been reading, but I know just enough to be dangerous. I am looking for straight forward resources/walkthroughs for migrating from NT4 to Win2000.

I currently have 2 servers. First is NT4/Exchange 5.5/tape backup/PDC. Second is NT4 file Server/BDC. Single Domain.

We will be purchasing two new bare bones servers to replace the existing equipment, but will reuse some of the hard drive from the current NT servers. Fresh installs of windows 2000 and will probably upgrade exchange 5.5 to 2000. And upgrade to Active Directory. I am most concerned about the move to Active directory.

Thanks