[TippeX]

c, delphi etc are all high level languages, they are compiled to assembly language by the compiler, so having experience in c can help but you really also need to know assembly so that you can change the instructions in the compiled exe.. a cdcheck can be done via various methods, the most simple being a call to GetDriveTypeA which returns 05 if the device passed in the parameters is a cdrom drive, so you then find the procedure that does the cdcheck and 'help' it so it returns 'hey there is a cd present, all is ok' back to the code, which then continues on... thats an example of a simplistic cdcheck, there are far far harder ones like on securom, starforce, safedisc etc... which most people can not 'bypass' as easily

in your examples, the 'differences' will probably be huge, and will be caused by the compiler, they will also be hex bytes which 'translate' to asm code, you won t see the 'code' you changed in a human readable form (like your c code)...