According to a story on The Register, the US is the source for more than 35% of all spam, world-wide, with South Korea second at 25%, and China third at just under 10% (all this according to Sophos).
Here’s the interesting quote in the article:

Sophos researchers say that an unprotected Windows XP computer (without any firewall, patches or anti-virus protection) stands a 50 per cent chance of infection by an internet worm after just nine minutes plugged onto the net. After 40 minutes there is a 90 per cent chance of infection.

According to a story on The Register, the US is the source for more than 35% of all spam, world-wide, with South Korea second at 25%, and China third at just under 10% (all this according to Sophos).
Here’s the interesting quote in the article:

Sophos researchers say that an unprotected Windows XP computer (without any firewall, patches or anti-virus protection) stands a 50 per cent chance of infection by an internet worm after just nine minutes plugged onto the net. After 40 minutes there is a 90 per cent chance of infection.