To what degree does the chipset affect performance?

The title of my thread pretty much says it, how much does your motherboard's chipset affect performance? I'm not talking about features such as more pcie lanes or usb ports, but rather actual speed/performance in things like games, processing-intensive applications, and start-up time. Or maybe it really doesn't make any difference at all? Suppose I were to upgrade from a board with an nForce 550 chipset to one with an nForce 750a chipset, while keeping all my components the same (amd x2 5600+, evga 9600gt, ddr800 ram, sata hard drives, win xp sp2, onboard audio), would I notice a performance increase in any situation? I know it's probably difficult to tell and that there are many different factors that will determine performance, but if anyone has any insights into this, I would love to hear from you. Thanks!

You will not be able to notice the difference in real applications. Chipset makes a difference in synthetic benchmarks of memory speed, and in very high overclocks. It is very much not worth changing the mobo for performance reasons. I would estimate 1-3% difference.

Where a chip set is capable of changing the CPU multiplier a noticable difference in performance can be demonstrated.

Edit:
I noticed after posting that Tom's has an article on the front page,
http://www.tomshardware.com/review [...] ,1988.html