As for paid AV I have Panda Security in one of my office. Had it a couple years there as I originally bought a long term subscription. I find it works very well with minimum effoert and low resource consumtion.
As for everywhere elso tho I have been running free apps, I 'll list them. The major difference in free/paid is you must update at regular intervals (I do it weekly). The rule of thumb in security is 1 AV,1 Firewall (preferaably not Windows firewall) and several layers of spy/adware protection. Further one should run their scans from Safe Mode.
My list (all free) and found in the BC Freeware replacements list. There are also Tutorials on how to use them. But you can always just ask if you prefer.
Antivirus. . AVG antivirus 7.5 ...
http://free.grisoft.com/doc/1Firewall. . Comodo Personal ...
http://www.personalfirewall.comodo.com/spy/adware protectionAdAware
http://www.lavasoft.com/products/ad-aware_se_personal.phpSpyBot S&D great at preventing browser hijacks,virus and spyware
http://www.safer-networking.org/en/download/index.htmlSpywareblaster
http://www.javacoolsoftware.com/spywareblaster.htmlSuperAntiSpyware (Free Home User version) One of the best Trojan and spyware killers
http://www.superantispyware.com/downloadfi...ANTISPYWAREFREEAS you go along an excellent tool is the
Hosts File. Read and learn how to use it from this BC tutorial
The Hosts File and what it can do for youGood luck