If they are selling a laptop without an operating system then make sure you get it at least half the ticket price. All the ticket prices I've seen include an operating system, whether it's Windows or Android.
Well, of course they want you to buy one of a paid security product (which they just happen to have in stock). They get a sale and the salesman gets a bonus.
Bet the charge is to upgrade from Windows 8 to 8.1, which is as Alex-Higham states is free of charge and you can do it at home.
I use MSE as well for my virus protection which is free. Other free options also exist including AVG, Avast and Kaspersky.