First, I think you mean Avast 4 (NOT Avant) antivirus? Is that correct.
Next, Windows doesn't have "virus protection". If you are referring to the Security Center warning which doesn't recognize Avast, then ignore that warning..It doesn't mean the antivirus program isn't working. It only means that the Security Center doesn't recognize Avast. In fact, I turn OFF all those Security Center warnings anyway. If you want to do that, open the Control Panle, then double click on the "Security Center" icon, then click on the "Change the way Security Center alerts me", then UNCHECK all the boxes, click on OK.
Next, if you're not going to use Norton, then you should uninstall it. Norton's installation instructions require the removal of ALL other antivirus programs while their program is running. If you want to leave it there temporarily, shut down Norton but opening the System Configuration Utility, (Start-Run, type "msconfig" (without the quotes), then click on OK), then click on the Start UP tab and UNCHECK all the boxes which refer to Norton/Symantec.
Hope this helps.