Re: need anti-virus!!
Steer well clear of Norton. Ineffefective in too many instances in my experiences, and updates were very few and far between. Maybe once a week. I now use Trend Micro which is doing a fantastic job and i haven't had any problems since i've been using it. It also updates as and when updates become available, which generally is at least once a day and often more.
Still ,do what i did and read as much as you can about any software you wanna use, and read as many reviews as you can find on the net. It took me a while but i finally went with Trend micro, a bit expensive but weel worth it in my opinion.