I spend way too much time on the net. I've recently needed to get a new anti-virus program. I've done some research and 2 names keep coming up as the best/most used free anti-virus programs, AVG free & Avast! Free. Can I trust these system since I'm not the casual net user. I run a small biz, & emailing is my life blood. I also do a lot of traffic on more dangerous sites like bittorrents and other file sharing apps. Does anyone have some recommendations on the best way to protect myself.

Many here at BC use either of those,they're highly recommended. if you use the free versions remember to update at least weekly. You are playing in some of the most dangerous areas of the net.
Please read thru these posts
Simple steps to keep your computer secure!
BEST PRACTICES: PC World's Avoid viruses & Scams
A list of other recommended and free malware protection apps are here L@@K
I recommend installing after the AV
Spybot Adaware
Spyware blaster
Superantspyware
Again update regularly

And one firewall to replace the windows firewall

Keep in mind that using any P2P file sharing program is a security risk. Even if you use a spyware-free P2P application, you still have to contend with the possibility of downloading malicious files from unknown sources and infecting your system. P2P networks have infected files on them and a number of them have malware that is included with their software. Using P2P software makes you susceptible to a smorgasbord of malware infections, remote attacks, and exposure of personal information.

Thanks for your advise. As for a firewall I don't use the windows firewall b/c I use a router as a firewall. I've found if I turn on the windows firewall it doesn't work well with the router. I then can't sent emails. Am I mistaken and a router should not work as a firewall?
As for the p2p issue is there any program to add security? What I've done in the past is DL p2p, bittorrent file etc.. onto an old desktop then run AV & Spyware programs on the whole HD. Then I feel safe enough to access the files on my main PC. Note -I generally do have the old PC networked thru a router all the time. Do you think this give me enough security?

No you are not safe enough with just a router. You are not safe with the Windows firewall program. There are several firewall programs that will protect your system. Firewalls only block what you tell then. You email should be able to pass through the firewall if you set an exception to allow it to do so. I personally like SyGate 5.6. It is simple and secure. Remember you should only run one firewall program at a time.

the aol active shield is a bare bones version of kaspersky av. i know, it's aol, but what i've heard from many knowledgeable people on several different sites, is that there are no dirty tricks associated with this programme. if i didn't already have a paid version of kaspersky, i would go with aol active shield.