"Microsoft has limited the number of free Windows 7 upgrades that can be claimed via its Windows Upgrade Option," wrote Silver. "Organizations need to understand their Windows 7 requirements and obtain rights for the best value," Silver said.
That's an odd limitation. Somehow I get the feeling that MS would cave to popular opinion on this point if pushed. Why limit upgrades to Windows 7 from Vista PCs purchased now? It kind of gives their promotion a black eye to limit it like this.