Norton Anti-Virus Uninstall and reinstall error.

I work for a major retail chain and I frequently install Norton Anti-Virus (NAV) on machine at the customer's request.

Here is my problem. Some machines (mostly HPs and Compaqs) have NAV 2004 trial pre-installed on the machines.

If I install NAV 2005 without first un-installing NAV 2004 I will get an error saying that I need to un-install and reinstall NAV 2005. The problem with this is that it is massively in-efficient to have my techs un-install NAV 2004 first or un-install and re-install NAV 2005 if they forget.

Can someone show me how to eather automaticall un-install NAV2004 with a .cmd file or fix the un-install and re-install error I get after words.

Thanks a bunch Rick G.