Alright, once again I am back with some laptop questions:

A)Let's say a laptop comes with a 15gig HD, and the user wanted to, maybe in the future, upgrade to a bigger one. Is that possible? I mean, we all know on desktops, you can just take the shell cover off and replace the HD, but how does that work in laptops?

B)Kind of the same general question, but this is for memory. Is the memory you get for desktops, the same kind of memory you can get for laptops? I'm more along the lines asking about size/brand...And/or is the way you replace them the same?

I would appreciate any help you could give. My knowledge of laptops is VERY limited.
Thanks.