Ah, you may be right. I've always heard it described as a kind of straw man because you are discrediting an argument by discrediting your opponent in a specific way.

That's probably ad hominem you're thinking of. "Straw man" is probably best described as putting words in someone's mouth - it's when you attack an argument that your opponent hasn't actually made instead of attacking their actual arguments.

Fallacyfiles.org is a really good resource for this stuff as well as wikipedia: http://en.wikipedia.org/wiki/Category:Logical_fallacies

Anyway I hope I'm not being too pedantic. I think logical fallacies are like programming anti-patterns - the terminology's less important than being familiar with the sketchy patterns so you can sniff them out.