Uhm rofl. What do you think the function of a virusscanner is? to PREVENT viruses(and other malware) to get on a computer.
But bleh i hope you get that demo running anyway, and if you do i'd suggest getting a new computer first (especially a new video card, i'd prefer a radeon 9700).
Never argue with fools... They will only drag you down to their level, and beat you with experience...