Mega Defender Installation Help
If all environment settings (comp mode, colour depth) are correct, all game files and all registry keys have been copied over correctly (I take it you made sure of that), then it's most likely an architecture problem.
In some cases, 32bit games just plain refuse to work on 64bit machines, then you'd probably be out of luck. You could however still try setting up a (32 bit) virtual machine and running the game within.