Of course you have to uninstall Norton. Never ever keep two or more anti-virus tools running on the same system. You'll probably have more problems than you can imagine trying to uninstall Norton. Norton is resouce hog and it doesn't deserve to run on anyone's system. Biggest problem is 'cause it's not so easy to uninstall it. You think everything is clean, but it's not... there will be tens of Norton registry keys left even after complete uninstall. Search the web for Norton uninstall tool or even better, search these forums for my friend RejZor's application. It has Norotn uninstallation tool integrated, so it will be less of a hassle to uninstall that monster.
Avast! is great, avast! is best. You'll see that after few weeks using it. Avast! Home Edition is free and best of all, you have free technical support at any time in these forums...
Welcome and stick aroud !
S.Z.C