Just a while back there was a report published about the benefits in desktop machines having 2GB of RAM over 1GB. As notebooks begin to take over a lot of the desktop playing field, though, it's interesting to find out whether or not you can see the same sorts of improvements in laptops. The playing field is quite different there, with smaller form factors and pricier modules, different chipsets with different features. There's an interesting report that covers exactly these topics. The subject in particular is a Pentium M based laptop that uses the newer chipset supporting dual channel memory (something sorely missed on earlier Pentium M chipsets).
What's interesting about the review is what it makes you consider about the importance of RAM in a laptop over a desktop. With a laptop, for both battery life and performance, the more RAM you have, the better. Laptop hard drives tend to be much slower than desktop drives, and though they don't use up much power, they use more than RAM does. The more memory a laptop would have, the less frequently it would need to access the disk. Less paging operations, more prefetch space (both in Linux and Windows), faster access times to cached data, more room for large-footprint programs, et cetera. While the performance gains aren't linear, they are across the board. After reading this you may want to take a bit more consideration into how much RAM a new laptop would come with and whether or not you could upgrade it.