Sorry I should've clarified myself better, what I meant to say is if your OS is up to date with patches & security updates & your running up to date antivirus. Your odds of getting a worm are pretty slim, I'm on the Internet minimum of 6hrs per day 7 days a week, 365 days a year (I know get a life) & in the last 6yrs I've only ever had 2 or 3 viruses & they were caught by Norton everytime. 99% of the PC's infected right now by trojans, worms & viruses are PC's where people use poor email practices & don't keep there OS & software updated.
I build PC's for family & friends & I usually run the PC for a couple days before sending it off to it's new home, well the last two I built, I had back within a week because they were loaded with viruses. When I fire up the PC it turns out they've turned off the firewall & several of there saved emails are infected with trojans, .exe files to be exact. I ask them why the firewalls off & they say because it kept poping up messages & they got tired of closing them. I ask them why they openned the emails & they said because they were from their friends, so they should be safe.
Yes reformating will rid the PC of the infection.
