are you using winXP, macintosh, linux or unix?? are you sure you don't have winXP firewall on? are you sure you don't have a router? because let me tell you, you are definately being protected in some way... you just are not aware of what is protecting you.
i mean really, do you beleive you have a magical windows computer that is immune to virus's with the exception of MAC, unix, and linux? if so would you like to sell me your machine?