Windows tends to react badly to this(changing hard drives. I have had it work sometimes....120gig to 15 then back for tests and it worked....there was only 7 or so gigs on the drive) causing lots of BSOD's. Normally a repair install will fix it. Any kind of disk imaging software should allow you to copy. I used to like Norton Ghost for this task, but it has been a long time...

What is the problem you are having?