|No you can't do that.|
First issue is odds are the new hardware won't support the old drives. Those are ide and my 2008 hardware did not come with ide support.
Second issue is AD isn't dos. You can't preserve the user accounts only the data which for K8 is nothing except for the teachers/administrators.
Only way to preserve the user accounts would be to do a upgrade.
Here is a good start:
Before you can consider this you need to free up disk space and lots of it. 100mb free means the servers are about to die and will not get up. Servers simply can't operate with that little headspace. I am surprised there hasn't been a catastrophic failure considering the age and lack of disk space.
Might want to consider bringing up the new servers on a standalone network, configure everything and have it working. Then backup/restore the user data. Then drop the 2000 servers and replace them with the 2008 servers. All that is left then is to join all the pc to the new domain/forest.
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