One thing windows 8 does well out of the box is resource management, but we both know 7 and vista use around 1GB of ram but that's subjective as it's usually a percent not by the GB. I have 64 so 10% would be 6.4GB not exact but you get the idea as it's based a percentage for optimization.
One thing I wished they kept from Xp and Vista was the traditional taskbar that we've had since windows 95, no fan of the super bar and believe you me even my 8 box is getting a change even if I have to hack it to use kde 5.0..
Here is a few tips to making your vista/7 box faster.
1.) replace the windows shell, there's a few shells out there that aim to keep the traditional look but use less resources, and there's those with the goal to be lightweight minimalist.
2.) Replace the taskbar, everything in windows is customizable but it's harder to get to without knowing what your doing or as easy as linux.
3.) Fine tune your DXDiag, a fine tuned DxDiag will make your apps run faster, use less memory than XP(yes XP was a hog, even more so than vista, vista's issues was with drivers and released too soon).
4.) Alternative Desktop Environment, there is a few alternatives to the windows desktop. One of them is KDE, Xfce has plans for a windows port as well. Cairo is also in the alpha stages.
5.) If you don't want to replace, than use Windows Classic theme, turn off hardware acceleration as you don't need it, and configure your dxdiag.
6.) Add more ram, adding more ram will improve your computers performance