Windows 7

Right click the Desktop > Personalize > Theme or Window Color

This will also change the color of Window borders and the Start menu.


I've not found a way to change just the taskbar alone.

+1 Me neither.

some custom themes can change the task bar.
You first need to patch a few .dll files.
http://www.withinwindows.com/uxtheme-patches/
then you can find custom themes. deviantart.com will prob. have some nice ones