I just bought a new laptop from Best Buy this weekend and was told the same thing. But in my case the salesman told me that their "Geek Squad" had already "tweaked" the laptop to supposedly optimize it's performance and remove some of the, what he termed, "junk" on the hard drive. He also said that this service included making a set of recovery disks which were included in the box with the laptop. The price for this extra service was $70.
Normally, I roll my eyes at this unasked for "bait and switch" tactic to raise the price of an item, but having gone through a problem several years ago where recovery disks were a life saver I figured it was worth it considering that the laptop was only $349 and I was financing it anyway.
Long answer short, if no one here can supply you with an easy, do-it-yourself answer you might want to consider giving their Geek Squad a call.
