Help - Will upgrading to 7200 rpm hdd increase laptop performance

I bought a toshiba L650 laptop with core i3 350 cpu, 320 gb 5500 rpm hdd, 4gb ddr3 ram and windows 7 64 original os in january 2011.

I am happy with it. But i think the slow hdd makes accessing files and programs slower. Even my 6 year old amd 64 desktop can access files and programs faster than that. Note that the os loads pretty fast. Is there would be any benefit by upgrading to a 7200 rpm hdd? Will it violate the warranty? Please help