The recent DDoS attacks on SKorean and US websites have been found to have originated out of the UK, with analysis indicating an estimated size of 176000 botnet-controlled PCs! The master host was also found to be a Windows 2003 Server machine. Seeing as the IP address is known, it will be interesting to see if the UK will work with the US and South Korea in determining the responsible parties.
The top 3 countries having zombie PC’s involved are Korea, US and China. I think that a large part of the issue with zombie PCs ( especially those from the east ) is that a lot of these machines are running illegal copies of Windows and therefore do no have access to Windows Updates. A quick cure would be a transition to OSS software which does not require onerous licensing and costs, and updates are part and parcel of the free offering.