There are a ocuple of issues.
You should have been able to copy the AC folder on the XP. If you couldn't there may be a problem with your hard drive.
You may have to go to amazing utilities and on the first menu, disconnect from the databases, otherwise it will say databases are busy, then you should be able to copy it.
I haven't a clue why your import items won't copy. Again, I am suspicious about your hard drive.
Another option is to take a backup off the XP and reinstall into the Vista. Make sure the XP has the latest version. I believe (and could be wrong) anything before 4.0.52 needs to be updated to play with 4.0.60. Perhaps the differing versions is why it is asking for a database tuner.