I recently bought a Dell SC440 on special offer at a really good price. I decided to move my WHS from an old AMD sytem built of bits out of the 'pre loved' category.
I moved the drives, loaded the dvd and it asked me to do a re-installation. About 1-2 hours later it was done, i re-activated online without problems, re-created the users, reloaded the connector software. After 3 hours the system is back as it was before running fine on a different platform.
The only problem: the chassis is a bit taller and doesn't fit where it used to be :-(
So it worked for me with no problems and it was painless.