Replacing Laptop GPU?

Hey there,

So, I am currently running an HP DV6700 notebook, but it's only got a 256. It didn't occur to me that this could be a problem until after I had had the laptop a few months and I tried to play some games on it, such as COD4.

It has 4 gigs of RAM, and a 2 gig processor, so everything else is fine... but the GPU appears to be a hair on the gimpy side for anything intensive.

After some research, I determined that an external card would do me no good. I've built towers before, but I haven't performed surgery on a laptop, and I don't know a ton about their hardware. So, my question has a few parts to it.

1) Can I swap out the GPU's like regular video cards?

2) If so, about how hard is it?

3) What is a good 512 GPU(possibly 1gig, if it's not too expensive)? It's got a "Mobile Intel(R) 965 Express Chipset Family" right now.

Thanks in advance!

Don't most laptops have the GPU built into the motherboard?