I have Norton Anti Virus and just recently downloaded AVG 7.0 which comes with a firewall. Im not really sure which one is better to have. I think maybe AVG but not certain. Does anyone know?

While others will gladly add to this post...one major difference is PAY versus FREE.
Pay products requires you to spend money , but you can get a friendly, helpful and dedicated support person on the phone...if...disaster strikes.
Free products are great , but it is hard to get support. Imagine trying to post to their help forums (they don't reply to e-mails from FREE users) when your machine can't boot!

I used to use NAV and they spent HOURS on the phone helping me!

thanx for your help. out of interest which antivirus do you use now then?

AVG.
I wanted to provide both sides of the story.
Stay tuned to this thread as I am sure many will chime in and show you comparative studies between the various products.
I use Zone Alarm (free) firewall.
If you are somewhat of a new user, you may want to click the link in my signature for the "Security Classroom for Beginners"

I have used AVG for several years and find it as good as any other anti-virus; whenever I have scanned using a web-based scanner, nothing has been found that AVG missed. Definitions are updated on a regular basis, and even for the free edition, there is a semi-official user forum for help with questions or problems.
I always prefer to keep my applications separate, so rather than lump functions with one application, I use a different firewall: Sygate Personal Firewall (also free). My experience with bundled functionality from the same company is that by taking the shotgun approach, the functionality of each of the areas is watered down compared to applications each from a company that specialised in that area.

Regards,
John