This is for the average joe by the way. A customer wants a Win7 install on a laptop with two hard disks. She doesn't have any preference about how the disks get used.
In the days of Win2k/XP, I would have junction'd "Program Files" and/or "Documents and Settings" off to the second disk, but my experience with Vista with trying to junction the Program Files folder leads me to think this probably won't work (Windows Updates that involved anything in that folder would fail).
I'm probably going to put the customer's user folder on the second disk, and leave a backup icon that will synchronise her user files to a hidden location on the first disk, to make the most of performance. I just wondered if anyone had any ideas that would be suitable for the average user.