Yes and No,
There are some laptops like the ones from alienware that are regular PC processors and maybe regualr RAM. There are other laptops that use the mobile processors and SODIMM ram which is pretty much RAM that is half the size of regular RAM. To tell if a processor is the energy saving mobile one, the P4 would be the P4-M with the M desinating that it is mobile.
As for upgrading to PC2700, I really doubt it, because laptops tend to be very limited with their upgradability.