What's worse for Microsoft is that they may be setting an example for other government organizations. Some of the reasons cited are very common ones that can affect large departments and their willingness to upgrade:
The decision not to go with Windows Vista was made for a number of reasons, according to Bailey. Probably the most important one, he said, is the ATF doesn't have enough time between now and January to verify that all of its systems will run effectively on the new operating system.
When you have literally thousands of machines, getting sold on a new OS is tough. As it brings out, MS faced a similar setback with Vista in another U.S. government department, the Department of Transportation, who warned against upgrading to Vista due to compatibility issues.