DVD X Copy is practically useless because of some legal procedures. To copy DVD you can get DVD Shrink which is free.
Concerning if they are dangerous depends if you scanned them before installing them and if you set a restore point before installing them (in case they don't work).
The program in itself maybe good, it could be the crack! that could be hazardous. Many come with keygen (key generators) to give you a serial number for instance. Sometimes individuals may put viruses or worms and you may be infected. Also, if you are going to install a "hacked" copy of a program, be careful if you plan to upgrade.
