What is the easiest / most efficient way to migrate a Vista PC to a new Windows 7 PC?

You cannot "migrate" a Vista PC to a Win 7 PC if you mean to combine the overall systems. You can use Windows Easy Transfer to export your data files and settings from Vista and then import them with Windows Easy Transfer into Win 7. Windows Easy Transfer for Vista 32-bit is @ http://www.microsoft.com/downloads/en/details.aspx?familyid=09D80814-2A73-4245-A63B-8E780D0430CB&displaylang=en Windows Easy Transfer for Vista 64-bit is @ http://www.microsoft.com/downloads/en/details.aspx?FamilyID=30C4DA6D-0522-4D28-AAC3-CE9D70AC6A6APlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

If you are not concerned with the migration of files and settings, (with any OS), I would back up your data, wipe the drive and install the new OS. I am not a fan of any type of upgrades unless absolutely necessary. Visit: anITKB.com, an IT Knowledge Base.