There is no guide that I can recall but follow these steps:
1) Collect one piece of each PC that you have deployed in your environment.
2) Talk to your business users or send a SurveryMonkey e-mail to your users to collect the software they use day to day and they consider critical to their business function.
3) Retrieve the software and possible talk to the software vendors for “eval” keys if needed as well as find out if the software vendor supports Windows 7
4) Install all components (Windows 7 and such software) on each platform.
5) Obtain “test users” who can evaluate teh software on each platform.
6) Create and maintain a “scorecard” of the results of your testing with the test users.