Are 2GB of mem even necessary for a notebook?

Intel Core Duo L2400 (1.66 GHz) Processor
100 GB 7200 RPM HD
etc., etc., etc.

In what kinds of circumstances would notebook users even need
2GB's of memory? Just curious.

Okay, MOAR questions for you considerate fellows:
What are the factors that use up battery life more quickly in a notebook?
I heard faster processors (2.00-2.16) as opposed to (1.66-1.83),
Graphics card?
(950 Intel Graphics Media Accelerator v. 256 MB NVIDIA GeForce Go 7400)
What about Memory size, HD size, and the RPM of an HD?