I recently swapped the 5400 RPM drive in my Laptop for a 320 GB 7200 RPM one.
The change from 5400 ---> 7200 RPM had a bigger impact on my system performance than did upgrading from 1 to 4 GB of RAM. THE BOOST IN PERFORMANCE WAS PHENOMENAL and got my laptop running close to the performance of a mid range desktop.
From now on the first upgrade to any laptop for me will be to a 7200 RPM HDD.