Also see this page and the original link on
http://windowshelp.microsoft.com/Windows/en-US/Help/3af7e05f-4d2a-4af7-a168-9242f9093bb81033.mspx
Windows Anytime Upgrade: frequently asked questions
http://windowshelp.microsoft.com/Windows/en-US/Help/37070041-1b90-4433-be0c-ab2855841b981033.mspx
From the MSFT site but as far as money transactions, they tell me those will
happen via the original purchase site or the OEM:
Upgrade to another edition of Windows Vista
Applies to: Home Basic, Home Premium, Business. Which edition of Windows
Vista am I using?
If you want more features in Windows Vista, you can upgrade to another
edition. You can either buy an upgrade disc at a retail store or use Windows
Anytime Upgrade to buy the upgrade online, and then use your Windows Anytime
Upgrade disc or the Windows installation disc to complete the process.
You can upgrade from Windows Vista Home Basic to either Windows Vista Home
Premium or Windows Vista Ultimate. If you have Windows Vista Business, you
can upgrade to Windows Vista Ultimate.
If you're not sure which edition of Windows is installed on your computer,
here's how to check:
. Open Welcome Center by clicking the Start button , clicking Control
Panel, clicking System and Maintenance, and then clicking Welcome Center.
The edition of Windows that you are running is displayed with your computer
details near the top of the window.
To upgrade to another edition of Windows Vista
1. Open Windows Anytime Upgrade by clicking the Start button , clicking
Control Panel, clicking System and Maintenance, and then clicking Windows
Anytime Upgrade.
2. Follow the instructions on each page.
When the upgrade is complete, you will have a new edition of Windows Vista
running on your computer. To learn more about the new features that you just
installed, read "What's new in Windows Vista" in the Welcome Center, which
you'll see on your desktop, or search for "What's new" in Help and Support.
See also
Windows Anytime Upgrade: frequently asked questions
http://windowshelp.microsoft.com/Windows/en-US/Help/37070041-1b90-4433-be0c-ab2855841b981033.mspx
CH