Installation failure NAV 2011

I downloaded and saved norton antivirus 2011, When I run it the installer says my OS is incompatable.Windows XP home circa 2005.

I did this same thing on a four years younger system with the exact same OS and it loaded and installed no problem. Worked flawlessly on windows XP home till that computer died of hardware failure.

So I packed the case back up with hardware on my old 750 mhz athalon mb, and reloaded XP on it.

The motherboard is a 2000 model gateway.The other was also a gateway.

I'm not sure if the age of the system matters.I have bags of ram and the hard drive is fresh.

XP home is performing flawlessly on this system so I don't think the mb is an issue.

Installer message is simply red letters saying the operating system is not compatable with the installer.

Yes,I downloaded the windows/etc,etc,etc for exp etc.version of the package.

I hope you can help me cuz I'm getting hammered here.This has taken a half hour to type due to lagg.