After chrome.exe and eclipse, the most memory consuming app on my Task Manager's process list is DWM. I think i can give up on some effects to gain more memory.
I don't think you will save much memory unless Microsoft is also removing desktop composition. When I turn off transparency in Win7, the amount of memory used by DWM.exe does not change.
Transparency is one of the features of DWM. If you want to get rid of DWM, you have to select Windows Classic theme.
And you could have been doing that all along simply by changing your theme.