Where can i find performance benchmarks of Adobe CS4 on Windows 7 compared to Windows Vista ?
I think we'll be hard pressed to find something as specific as this
But based on other benchmarks I don't expect very large differences in performance between Vista and 7, mainly because 7 isn't all that different.
I think you would do better by looking at results from benchmarks like 3Dmark or PCmark, since nobody uses Adobe CS4 exactly the same way and then what's the use of the results?
Mainly it will be up to you to decide whether you feel Windows 7 will offer you improvements you might require. I recommend this article by Anandtech on Windows 7 performance for more info.
Besides you should note that Windows 7 fixes some problems people had with Vista and personally I think it's a nice GUI improvement as well. Making an OS more pleasant to work with can be important as well.