Here's an interesting post from Harry's Place which captures some interesting conversions from the far right to extreme Islamism.
I reckon it's not that big a step - particularly if you're fueled by hatred of the joos.
Commenter Wardytron nails it:
Plus they’ve seen that you get far more indulgence and less outright hostility as an Islamist as opposed to a neo-Nazi, the ideological leap is tiny - you get to keep all your enemies - gays, Jews, liberals, women - and you’re joining a movement which, if not actually flourishing, isn’t down to nearly single figures. I’m surprised it doesn’t happen more often.
I guess one thing that makes it hard to make the transition to Islam - even the violent, nasty political hate-filled kind is having to give up beer.