Is it worth it to replace the hard drive of a never turned on Macbook?

[Guest]

I'm buying a Macbook today and realize it would be cheaper to buy the 160gb laptop, and switch out the hard drive to a 320 gb (its only $76, compared to the $300 difference between the 160gb macbook and the 250gb macbook).

I picked out the hard drive and I know where the hard drive in my laptop will be located, and how to remove and replace it. However I'm a little worried about actually doing it. I wouldn't need to back anything up because I haven't used it before, so can I just replace the hard drive before I ever even turn it on for the first time?

Also, I've never done this before..
What are the risks I'm taking by doing this?
and, is it worth it?

 

[Ijack]

Obviously you'll be saving a bundle. And Apple do, amazingly, sanction this end-user upgrade, so there's no question of losing your warranty if you follow their instructions.