Many corporate and private computers have installed “standard” set of free programs and utilities which users use in everyday work. You use them for sure as well, Adobe Acrobat Reader, ICQ, Skype, Irfan view, Quick Time, iTunes, Firefox, plugins as flash, shockwave, Sun Java and many others. As it is usual, in every piece of non trivial software package is a hidden bug which just wait for discovery and if possible misuse with no exception for those above.
What is good that some of them have incorporated automatic patching function (like Adobe Acrobat, Quicktime, Firefox) but these mostly work only when logged as Admin and others don’t have anything. So after all its up to user to watch security lists like that in Secunia or just install every new version wherever available which is quite boring and nobody is doing it.
One nice option which is offered by danish security company Secunia for free. It is online (as Java applet) or offline (Secunia PSI) security scanner which “know” what vulnerabilities in what piece of sw is known and will tell you that. All the rest is up to user so he’ll install recommended new versions. Better once for a time than never. Self describing info can be found at http://secunia.com/blog/20/ which is telling that 81.01% of all Windows users that run Secunia’s security scanner had some piece of installed sw vulnerable to hacking.