Interesting thread - especially as I'm reading this at the mo, and the issue of political violence has been on my mind a lot the last year:
http://profile.myspace.com/index.cfm?fuseaction=user.viewprofile&friendID=118803727
...it's not a thoroughly convincing case for militant anti-fascism, but a passionate and self-righteous one. In the book it's pretty clear that the fighting is an adrenalin-addiction backed up by a fevered moralilty. Fcourse you cant help but sympathise with these steel-toe capped crusaders, and no doubt it takes a shit lot of guts (though the criticism of 'macho bullshit' isn't utterly void), but whether its really necessary remains far from clear, and I cant help but feel that is probably isnt really.
Overall it seems like its violence for violence sake - when your dealing with scum fascists it's better just to win the intellectual argument: it shouldn't be hard to do... in fact, when is it ever easier?
Going back to the book, the 70's were a different age, so somehow violent anti-fascism all seems to make more sense back in that context - they were violent times all round. Not to say that there isnt a real threat to antifascists from fascists today, there is, and particularly in places like Russia. Basically Im pretty convinced that nonviolent methods are just as good, if not better, in almost all situations, so I guess my response is to be expected.
Talking of books and that, this book which i read a couple of months back probably makes the most convincing case for nonviolent action:
http://www.extendinghorizons.com/images/WNS_cover_for_web.jpg
I recommend it highly - I think its important to really get into the case for violence vs. nonviolence and make up your own mind. Peter Gelderloos' How Nonviolence Protects the State didnt really convince me...