Unsafe mac software

Hi ive recently switched back over to a mac!!!!! and am expecting my computer to arrive anyday.

anywyas ive become so used to windows that ive been skeptical with unsafe "cleaning" software can that potentially mess up ur computer.

my new laptop will come with snow leopard, and i was wondering if any of these softwares could be potentially harmful to the mac??

can onyx or mainmenu ever have potentially unwanted sideaffects??

what about ones like appzapper??