Vista Aero Theme looks cool because the nice effect of the transparent glass, but on some old computers or on computers that has low Resources e.g Video card, Rams, cpu.
It can make vista running slow especially when navigating through window, so there is solution for that we can Disable the The transparent glass to make windows vista aero theme run faster.

1-Click on the desktop and select Personalize.
2-Select Windows Color and Appearance.
3-Uncheck Enable Transparency.