I had the experience of upgrading from Microsoft Windows Vista (Business Edition) to Microsoft Windows 7 (Ultimate edition). Overall it was a very positive experience.
I prepared my PC for the upgrade. I did a BIOS upgrade to be sure that I have the latest BIOS.
I used the upgrade instructions from Microsoft. You can print the instructions to have them handy. I strongly recommend to run the upgrade advisor and follow the instructions. Uninstall any incompatible programs. You can install them after the upgrade.
Allocate plenty of time for the upgrade process. If you plan to use the Windows XP mode be sure your processor support virtualization. You may have to manually alter the BIOS to enable virtualization.
If you use Microsoft Virtual PC 2007 you should close your virtual machines (shut-down) and remove Virtual PC additions. If your virtual PC is not working on Windows 7 you can always create a new Virtual PC and use virtual hard drive from the old Virtual PC. This last solution worked for me fine.
I ‘ll be happy to read about your upgrade experience.