I recently installed windows 7 (non SP1) and I didnt even do anything and I got hit by that sysguard crap. Couldnt run anything, not even task manager. All I did was go to amd (thru msn default page) to download the lastest drivers. Somehow in that process I got infected. This was literally 3 minutes after install was finished.
Of course I've seen many computers get infected with that crap even though they are running norton, avg, avast, etc. I think a computer just needs the latest updates for 99% protection from what's out there.