Maybe in certain high-end video programs, or trying to run a dozen VMs, or other highly specialized application, but in general use, gaming, most anything else, not at all.
If you're gaming and browsing the web, you'll be fine.
If you're doing any video authoring or heavy-duty Photoshop'ing under Windows 7, you could do with another couple of gigs.
I would sweat Max1s's suggestion that you move to DDR3-1600; you probably wouldn't notice the difference between 1333 and 1600. Just go with what's cheapest and what works at 1.5v DRAM voltage.