The only things I can think of is to make sure and go back to the checklist for Vista
http://www.mtu.com/upgrades/hoster/v...de-hoster4.htm and make sure nothing has changed. It has been reported that some updates from Microsoft have changed some of these settings like turning the UAC back on.
The other thing I would suggest is to defrag both drives to speed up files transfer.
The 2 320GB drives you mention are these internal or external USB drives?