Is there an easy way to re-install programs?

Hi,

I have a slightly odd problem and am wondering if there is a simple solution. I like to re-format my harddisk on a regular basis, say about once a quarter. Re-installing all my programs (and the OS) is pretty time consuming and boring. I’m wondering if there is a simpler, automated way I could do it so I would not have to be sitting in front of the PC and it would go on by itself? Given that after the OS has been installed, most of the other stuff, drivers and software are avaliable on a seperate partition? Any suggestions?