There shouldn't be any compatibility issues, but I wouldn't spend the money on Registry returns too many false positives for my taste. For instance, I downloaded/ran the trial some time ago, and it came back with nearly 1,000 errors, with over half of them being for Microsoft Encarta and Microsoft Money. What Registry Mechanic didn't know was that those two programs were correctly installed and operating, and removing the registry entries listed would cause them to stop functioning normally, forcing their reinstallation. Thus, despite it catching nearly 300 legitimate errors that other registry cleaners missed, I went back to my trusty RegCleaner and CCleaner (both free), which are much more trustworthy, IMO. However, if you're willing to take the time to verify each entry prior to its deletion, Registry Mechanic will be a powerful friend for many years.

Hope this helps,