I ran MS starting with MSdos (with DosShell -woo hoo). Ran 98 for 10 years until we bought the new box (with Vista - Thank you MS for getting me on Linux). Never had a virus and only one piece of malware (deep mining for info deal) that only lasted 15 minutes.
I am not real worried about getting crap on my Ubuntu OS because we use the same habits that we did with 98. I think if that security hole was as safe as it was, Ubuntu is pretty much solid.
People get malware on Win from being stupid (mainly). The biggest threat to your security is the person on the keyboard.