I can recommend the free Avast anti-virus version. Although you'll probably want to turn off their new "auto"sandbox mode as it's quite overzealous. Luckily just a checkbox to get rid of, though.
And Norton can definitely be a pain to fully get rid of. First you need to uninstall it from your Add/Remove Progams in Control Panel (if using WinXP) and make sure to select the Main Norton program to uninstall - the others will usually point you to which that is, if you do try to uninstall the wrong one first, but ya never know with Norton's un/installer. Norton, as a whole, has been quite a pain in the rear for awhile now and you likely won't miss it at all.