@Reece
What do you mean Zonealarm doesn't work with SP2 or 3 of course it does, well when i use to run ZA it worked fine with SP2 dont know about 3 but it should. I bet windows uninstaller hasn't deleted all the registry entrys so when you try to reinstal ZA it starts complaining. if you can delete the entrys your get ZA back on. I use Uninstaller 2008 which rips your harddrive looking for every single piece of the software your wanting to uninstall and makes sure its complelty off your drive when its done.
Oh is this a reformatted drive i remeber you mentioning something about reformatting your drive, then very strange ZA wont install on a clean drive.:hmm:
Otherwise you can try out the shareware version of "Your uninstaller" here:
http://www.ursoftware.com/download.php