AVG, without a doubt.
There's a free version called AVG Free that is available at no cost for personal use. Hidden away on the AVG website pretty well, but you can still find it if you do some digging. Probably easier to locate through www.majorgeeks.com
Direct link: http://majorgeeks.com/AVG_Free_Edition_d886.html
There's a free version called AVG Free that is available at no cost for personal use. Hidden away on the AVG website pretty well, but you can still find it if you do some digging. Probably easier to locate through www.majorgeeks.com
Direct link: http://majorgeeks.com/AVG_Free_Edition_d886.html