a2 ain't bad..........but there are plenty of others....stand-by to be inundated by more from the trojan whacking brigade.... Cochise,
You can get A2 from Here. There is also Ewido a more finish product in my personal opinion. None of them have a realtime-monitor in the free versions, only scanner. Ewido is the only one with daily updates. Have fun.
There is also Ewido: http://www.ewido.net/en/ and the A2 site is at http://www.emsisoft.com/en/software/free/ I hope this helps.. Sorry, Don was quicker at the draw.