Perhaps you’ve seen this article in the Washington Post. Therein, their resident security person (blogger? reporter?), Brian Krebs, gives some advice about how to avoid getting pwned when you want to do some online banking. The advice? Use a Linux LiveCD to do your online banking.
Throwing in Knoppix or running Ubuntu live is a great way to get around this problem. Although I’m sure it’s possible to exploit the OS while it’s running in memory, the current operating system installed base climate means that the odds are enormously against it, even when you set aside the added security of a GNU/Linux OS running ephemerally, in read-only mode.
Ultimately, however, I have such mixed feelings about this situation. Among the worst outcomes I see is that people get really paranoid about doing anything with computers because it could screw them over. That’s bad for everybody in the computing industry, and, frustratingly, it doesn’t have to be that way.