The 8GB make a very positive effect especially noticeable when using Paralles Desktop 8. I use Windows 7 64 bit under Paralles Desktop 8 as VM and Windows and have assigned 7 2GB of RAM. Thus, in addition to Mac OS X Lion and Windows 7 runs under Paralles Desktop 8 without any delays.
A productive work with programs for Windows (need this for my work) Nothing stands in the way!
Positv noticeable make the 8GB of memory but also on MacOS X Lion, particularly in connection with a built-in SSD hard drive !!
Conclusion: Compared to previously 4GB of memory, the upgrade has definitely paid off 8G GB of memory! Here, this kit of Corsair works fine with my Macbook 13.3 (late 2008)! Strong buy recommendation!