Analysis of the net addresses where the e-mail messages originated showed that more than 100,000 hijacked home computers spread across 119 nations had been used to despatch the junk mail.
So, surely one way to combat spam would be to educate people to use proper protection for their home computers, or better still, have a system built into Windows, (and other operating systems) which prevents them from running without adequate protection being installed and updated. SP2 does this to a degree, but I think it should go one step further than just nagging users if they don't have protection installed, and disable all network facilities until it is.