It bugs you with full page ads for the paid-for product, unlike the other two, and doesn't support Windows 9x. Otherwise, not a bad product, I don't know why it gets less mentions. It can be found at filehippo click here
Also if I remember rightly, the new free version doesn't check incoming e-mail, just relies on the shield function to catch any nasties if activated. It's ICSA and Virus Bulletin rated with a good reputation, but the nag screens brundle mentioned and the nature of the compromises made in the freebie put me off it. Which is a pity as its predecessor was a real low footprint nag free gem.
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