Please do not get me wrong over what you are about to read, since I have huge admiration for developers who create great apps for the Mac as Shareware or Freeware (and occasionally good value Commercial) downloads.
My concerns over this are:
1. Anyone subscribing to MacUpdate is smarter than the average bear, thus:
2. Anyone subscribing to MacUpdate knows the advice already posted by ZBOB - the best anti-virus defence is planted between your ears, and
3. How responsive can the developer guarantee to be when (NOT IF) an OSX virus gets into the wild? It takes a significant amount of monitoring and resource to implement an update to the filtering.
The developer, PC Tools, offers no information about its history, size or structure on its web site. For all I can tell, this is a script-kiddie working from a garage. And the name PC Tools suggests a Windoze oriented operation, despite well-written copy telling me that everything is Mac oriented and does not bloat the apps database with Windoxw only virii (aka "viruses" for the illiterate).
I know that Macs are in the frame for attacks from the e-vermin, and I also know that every single major AV vendor has given up trying to flog their wares to Mac users, for good reasons: there has, until now, been no credible threat. The time is therefore right for a dedicated and serious Mac software developer to come out with a product, that if it delivers, could easily become dominant.
Meanwhile, I will not download this valiant (maybe?) attempt, as the cynic in me says that this is more likely an attempted sale based upon FUD - Fear, Uncertainty and Doubt = buy now; better safe than sorry.