Allen,
Let me answer your questions in order:
The first is because I'm not completely clear on the ramifications of the Software Assurance Program. If I upgrade the XP Home to XP Professional, is the upgrade from there to Windows 7 free due to the SA Program or is there the additional $8 to upgrade to 7 Pro?
If you acquire XP professional licenses, they are indeed upgradeable to Windows 7 through Software Assurance either free by download or around $25 for a reusable disk.
Second, to upgrade the Vista Home Premium to Windows 7, could I also "upgrade" it to XP Pro and then upgrade from there to 7 via the same SA Program?
It seems that after XP, Microsoft has discontinued the ability to what I call "cross upgrade" (or downgrade) between the two product lines of Home and Business / Professional editions. You cannot legally downgrade or upgrade Vista Home to any Professional or Business edition.
Finally, I believe there is a 5-seat minimum in an order, correct? I know that you have the special one-time program for Windows 7 where that minimum doesn't apply to orders which are just Vista and 7, correct? Does that special program also apply to XP upgrades?
If you are only requesting either Vista and / or Windows 7 products, there is no minimum seat requirement.
Please let me know if you have any other questions.
Autumn