if you can afford to buy original copies which you can update daily, why not use nod32. AVG free gives you the protection u need without paying for it. and it can be updated daily too.
Norton eats lot of memory. not AVG. I think AVG is the best free antivirus. Read from some site early this year.
AVG free + Spybots + Adware gives you complete protection for malwares..
don't forget also registry fixing software since AVG spybots and adware do not correct or heal your registry entries if it was changed by the virus..