You don't or shouldn't have to if the software is written properly. One of the reasons I detest s/w like Norton/Symantics products (Ghost excepted, top program!), too many hooks into files it shouldn't haveOriginally Posted by scm
That is because of the need to make the OS accessible to some users who are not that au fait with computers and would struggle if everything was locked down IMHO.
Again large user base means more malevolent threats and attacks, something MACs and Linux users don't have to contend with due to not really being worth it with the relatively small numbers.
My main source of free software is download.com as the software is checked and the risk of virus or malware is much reduced, never had a problem from there personally