What type of applications are you running with your pc? Unless you're doing something that is disk intensive, you'll hardly notice the difference between a 5400 and a 7200.
Is it better to have a 5400rpm hardrive to conserve batterylife/a little money or a 7200rpm hardrive to keep the speed and forget battery life. And if I was to get a 5400 how many minutes on average would I really save.
By the way I plan on keeping this laptop for a good while. And I'm thinking around 80-100 gig drive.