system() PHP newbie!!

Hi, I want to use the system() command for some encryption! I can't get it to work and so am trying to just get the system() command to run any program!! There is not much (in the way of examples) on the php page and was wondering if any one could give me a few pointers? I have an apache server running on win2000. If say I wanted to run a program called temp.exe in the root directory on my machine is it a matter of just adding the line: system("C:/temp.exe")?? I have also tried system("C:\temp.exe)!! This is probably a really silly question but I am new to PHP (and it is my first scripting language!!) Could someone send me an example or tell me what I am doind wrong? Any assistance is very much appreciated, Kevin Connolly.