I LOVE mozilla. I've tried several and keep coming back to it.
I use the antivirus that comes with my provider (Etrust EZ antivirus). I also use the AVG, but was worried about conflict and removed it, though it was great. Also, I didn't know that I had a complimentary virus protection with my server, so you might want to check there.
I read a recommendation to download (all free) CW Shredder (finds and gets rid of CoolWebSearch stuff), Spybot and AdawareSE and run them in that order. I do that and they all work great for me!!!
KD