If you are doing an experiment then I'll be interested in seeing if something happens to your machine... Please let us know. Otherwise a computer without a decent AV nowadays is like driving a car in the middle of gun fire. Even one of those freebies AVs might be useful, warning you of an intrusion and giving you enough time for a quick reboot. I read in another post that even in 'shadowmode' a trojan could theoretically reformat your HDD... If it is indeed possible, you might have difficulties starting windows again upon rebooting.