Three Options that Help You Understand and Resolve Windows 7 Compatibility Issues
Option #1: Use Windows 7 Upgrade Advisor to check if the hardware on your existing computers is adequate;
Option #2: Use Microsoft Application Compatibility Toolkit 5.5 to check if your applications can run on Windows 7 and how to resolve compatibility issues
Option #3: Run your XP dependent applications in XP mode on Windows 7.
To find more detail on the application compatibility issues, check out this blog post.