That message (mismatch) means that it recongises the disc was originally USA and it is now PAL (after you patched it).
This is basically a good way to check what the region is of a game, sometimes people release a USA game and patch it to PAL, this program will tell you if its truly a PAL game or patched.
Bigs is quite good, controls take some getting used to, but its good. I liked transformers too, pretty graphical game, impressive.
Im back to playing Resident Evil 4 for now though, would like to finish it!