"But when you're still providing us with Windows XP in 2011, you are doing it wrong."
Sigh. So, you have personally checked out all software the enterprise runs under Windows 7 and will be willing to bet your job that it all works perfectly with no hidden issues have you? Here's a hypothetical situation for you:
A company has a software package that they run on 70% of their desktops called DerpMaster 2002. This is an important software package as almost half of the company's business is recorded in it. It works fine under Windows XP. In late 2010, the company decides it's time to upgrade their desktops to Windows 7 as the company president uses it at home and wants to "move with the times". The CTO doesn't see any business reason to move the company to Windows 7 as all of the company operations work well under Windows XP and Windows 2000 Server as they have been the last several years. At the president's insistence, the migration proceeds.
After a month's operation, end users and the IT department are starting to notice that there is random corruption of records in DerpMaster 2002. The first couple of times it was encountered the corruption was considered a random happening or disk fault on the fileserver and the affected record was restored from a previous backup. But now it's happening with a frightening frequency. A random sampling of the DerpMaster database of 300,000 customer records is taken and it's determined that up to 5% of random sample shows some form of corruption. That means there could be as many as 15,000 records corrputed. A series of calls to the makers or DerpMaster 2002 reveal that on small databases their own testing of Windows 7 showed no adverse issues, but they were able to scale up testing and show in-house that on a database of the size and activity level of the company's, there does indeed seem to be a problem with the application. Of course, DerpMaster 2002 is NOT certified for use in Windows 7, but DerpMaster 2011 is, and lucky them! They're willing to provide upgrade licensing for only $500 per seat!
So that sorts out the cause of the problem, but now the company has a database where 15,000 records out of 300,000 are potentially damaged. Rollback to a database backup prior to the migration is out of the question due to the thousands of transactions per day entered into the system. The only course of action is to spend enormous manpower manually checking and correcting if needed all 300,000 records. The system has to remain operational while this check is done, and further corruption has to be prevented. DerpMaster 2011 is a brand new product, based on an entirely new database platform and as such the CTO has difficulty believing it to be a safe upgrade until its track record is proven. To address the problem of corruption, all desktops are given a Windows XP virtual machine image, to run DerpMaster 2002 in. Over the next two weeks (with the IT staff pulling an average of 3 hours of overtime a night) the corruption in the database is eliminated and operations return to relatively normal. Except now the users have another level of complexity on their desktops accessing an application through a VM interface.
Oh and by hypothetical I mean it actually happened. So that's why IT departments get annoyed when someone tells them that switching from a proven platform that works for all company functions to a new platform because an end user thinks they should get with the times or they're "doing it wrong".