Not necessarily a 'need'...more of a luxury. 5400 comes stock and works great. But while some argue about the heat generated from a 7200 would (in theory) be greater because it moves faster (thus using up more battery life), I find that a 7200 is more efficient and processes things quicker, which means it doesn't have to work as hard to do the same amount of work (which offsets the speed, maintaining the battery charge) . Some people can notice the difference, others can't. If you're just using your computer to listen to music i'd say the 5400 would be ok. (then again, i'd say just having an ipod would be ok too) But if you plan to use your computer for anything that involves processing information (burning dvds, transferring data, etc) I'd say the performance benefit of the 7200 is worth the extra $50.