How should I safe guard my new laptop from viruses, spam...?

I just received my new Lenovo X220 from UPS. I will use it to run my staffing company so I want the absolute best security software that is available. I didn't add on the McAfee or Norton options when I built it because I've come to understand that they are useless. What should I buy or download to completely secure this laptop against all threats? I want industrial strength, overkill protection.