As I alluded to in an earlier post, Virtual PC 2007 is not supported on Vista Home Premium (teach me to RTFM next time!).
That being said, I've been running it at home using VHD's created while at the office, for both Windows XP SP2 and Windows Server 2003 SP2 guests, without any problems. It seems to be as about as snappy an experience as I've had to date when playing with virtualization.
The VHD's were created under Virtual Server 2005 R2 using sysprep to establish a base OS image in a VHD that I can then copy, fire up, screw up, and delete as necessary.
I'm not sure I understand all the differences between using sysprep, or just copying an existing VHD and renaming, beyond the possible SID conflict you might experience with a server product like Sql, or BizTalk, and a domain controller. I've not had any problems using the copy-on-create method with a Sql VHD, and then renaming the newly created instance when it first boots; I've only run the default instance of Sql to date and have no idea what it might do with a named instance (or clustered!) but I believe that you could probably rename it by following the books online.
For prepping a BizTalk VHD, its important to not actually configure the server until its spun up for the first time and has been named appropriately.
Your mileage may vary...
I do notice that I have the virtualization option at the BIOS level with my new Dell workstation at home. I've not yet enabled it to see what difference it makes.