Keep in mind that this thing is FREE:

Despite some outright dishonest flame reviews of iAntiVirus here at VT, it actually does work, mostly. I let it loose on a folder full of Trojans a friend shared with me and it successfully found MOST of them:

Trojan.OSX.RSPlug.C, D & F
Trojan.OSX.iServices.A & B

Problems:
1) It did NOT find Trojan.OSX.RSPlug.E, of which I had a number of copies in my folder-full-of-Trojans. That is upsetting.
2) It also uses wrong names for the iServices Trojans. But sadly, despite a clear naming convention for malware, hardly anyone bothers, which is of course pathetic.
3) The app only gives you two choices when it finds malware: Either remove the malware or nothing. There is no sophistication to this app whatsoever.

Maybe the 'Pro' version is way better. I don't know. The PC Tools website certainly 'claims' iAntiVirus detects all the current Mac malware. Judging from the free version, it only finds some Mac malware. Maybe I'll test the Pro version some time.

In the meantime, I own Intego VirusBarrier, which frankly is the ONLY anti-malware app for Macs I can recommend. It works great, detects everything, is updated daily, is entirely reliable, is never a CPU hog, and has all the bells and whistles you could want.

If you want to stick with free stuff, the best idea is to use BOTH iAntiVirus AND ClamXav. Between the two of them you're probably just fine. This is thanks to the fact that the excellent author of ClamXav went out of his way to convince the ClamAV project to accept contemporary Mac malware sample definitions. *Applause*