Using Pro/Engineer Wildfire 4 on Windows XP and (recently Windows 7)
The Windchill Client Components section of the Windchill 9.1 Software Matrices says Windows 7 is supported on clients beginning on Windchill 9.1 M040. What are the implications of running an earlier release of Windchill (e.g. 9.1 M030) with Windows 7 clients?
Most likely you will see no issues but when you call TS for issues, you will get the sorry, I can't help you message. That could be where they drew the line at regression testing but this is just speculation.