I bought my first Mac today, Air 13" from Best Buy (awesome deal BTW, $60 off on sale, then $100 coupon with .edu email, and tax free). Anyway, they gave me a free virus protection subscription for 6 months. I know Macs do not need it, but the sales rep said it will protect other PC users if I receive and then send an infected e-mail. Is this really needed, or just a waste??