I honestly didn't notice a huge difference at first, even with the SSD, but after having ran my setup for months, there is no going back. My brother has my old Q6600 now (which is running at 3.5ghz) and the computer is still quite responsive... but let's just say he can't exactly run 3 virtual machines in the background, and game at the same time, like I can.
Sandy Bridge is freaking
powerful, but for the users who just casually browse the internet and use office applications, they probably won't notice anything over the last generation quads.