Do i have to run full scan even if i dont have internet? when not in use i shut down comp..?

If you have not had any internet service since you`ve had your computer then more likely you need even need virus protection, unless you used a flash drive or something of that matter to hook up to your computer and it wasn't yours. Viruses are created by hackers, and they can only traffic them through the internet, unless they put them on usb flash drives and toss them in the street or something.