Help with this virus?

To be specific as possible,I recently got a new computer (2 months ago) and it came w/ Norton Anti-Virus 60 Day Free Trial.I heard it wasn't that good so I installed a free version of Avast Anti-Virus (I also kept Norton).Later I had problems with my computer,it wouldn't connect to the internet,or rather it could only connect to 64-bit internet (a very distilled version).A couple days later I try to connect to the internet,my regular 32-bit OS.What do you know,Norton uses auto-detect to pick up a Heuristic Threat that was stopping me from getting on regular internet.I say to myself "This will never happen again." A couple days later my Norton trial has expired but I don't care because I have Avast..I get the same exact problem.So I get on 64-bit (because that's the only one I can get on) and download Norton Free Trial.Guess What? Norton Can't load because of the same issue.Norton won't pick up the threat.Avast won't pick up the threat either.My questions are:

1.How to get rid of all of my viruses?

2.What safety measures to take to make sure this doesn't happen again?



I want every single virus eliminated from my computer,and to be able to get on the internet (Regular 32 bit OS) not 64 bit watered down can't watch nothin on Youtube OS.Please Help Thanks