safedisc2 ?
 

Anybody know of a site that lists the differences and the revision numbers. I went to the macrovision website and found nothing. :(

Hehe - as if Macrovi$ion would help ya.

All the difference are merely technical and don't really make much of a difference (except when you step up to 2.51). The difference between 2.05 and 2.4 won't be noticed if you are copying with a writer capable of 'correct EFM coding' or if you use a crack. But I believe that there's an ATIP check with every version after 2.4.
If you want to know what version is on a disk, download Safedisk Analyser and check the main exe with it.

Thanks for your help. :)