AVG, AD-Aware SE.
Do what I did. I made my own business cards and started giving them out to customers or anyone. My computer was paid thanks to those people who had all them virus/spyware. Also, lots of people now days want wireless dsl setup and don't know how....guess who they call?
As far as virus programs. I install both avg, adware and also comodo firewall for them. All these are free but I charge customers $35-$50 to install them. In lots of cases though, I'm forced to do a complete windows reinstall due to badly infected comps.
Hey, that's better than the $70 and up that bestbuy, circuit city or other places charge and they don't go to the customers house.
I make more money off of the repairs whether software or hardware than building a computer and selling it.
Anyways, good luck.