The top recommendation in this category is a2 (a-squared) [1].
For those of you who are average PC users who don't use an anti-trojan scanner, It recommend that you download a2 (a-squared) and scan your PCs weekly. It suspect that you may be surprised at what you'll find. a2 is also pretty good at removing some spyware infections, so bear that in mind the next time you encounter a spyware product that you can't remove with normal anti-spyware products like Ad-Aware.
High risk PC users, such as P2P file sharers and frequenters of hack sites, should also consider a paid alternative like Trojan Hunter [2].
[1] a2 (a-squared)
Website:
http://www.emsisoft.com/en/software/free/
Author: Emsisoft
Date: 04/11/2008
Version: 3.5.0.8
Download File size: 24.8MB
License: Freeware
Operating systems supported: Windows 98 - Vista 32bit
64 Bit Capable: no
Portable version available: no
Other languages supported: yes
Additional Software Required: no
[2] Trojan Hunter