Within the same family of models, price of a laptop computer increases along with the speed and processing power of the CPU and the amount of RAM. For most business and home users, the difference in performance between a middle-of-the-pack CPU and a faster and more expensive processor is not important enough to justify the added cost.
If you have the extra money to spend, you see a much more dramatic improvement in performance if you spend some of that money on additional RAM, especially if you expect to upgrade the operating system to Windows Vista. Your new laptop should have at least 512MB, with space for expansion to 2GB.