I always wonder about that crap...I never get this stuff (I assume by doing prudent things to protect my system), yet everyone that comes to me for help (I have since started charging to rebuild the system and instructing them to use things like firefox, ad-aware, spybot, etc, which made a HUGE difference in the number of help calls I have been getting) always insists that they didn't do anything...it just happened one night...
Exactly the same story here my friend. It seems to me that some people just cannot resist the temptation to open attachments and click on links?

BTW that second link is to a pretty good (free) dialler zapper