ClamXav is free. http://www.clamxav.com/http://www.markallan.co.uk/BB/
Personally I don't worry about malware on the Mac.
But I do keep ClamXav around to scan files that I will be sharing with my PC.
Intego, Macscan, etc have free demos. you can try them out to see if you like them, but they are not free.
Most Mac users will tell you that you don't need an antivirus. They say that it will slow your Mac down,
and might possibly cause problems, such as kernal panics. You can go a long way towards protecting yourself
by tightening up security on your Mac.
One website (of many) on how to harden your Mac. http://www.macshadows.com/kb/index.php?tit...dening_Mac_OS_X