Is your system slow or are you making it slow??
Unnecessary Windows Effects (Aero Glass) I know it looks great but it just consumes too much of your resources
go to perzonalize desktop dialog and change the color options, when there unselect the enable transparency checkbox (this is a mid point between Aero and basic Windows
You can also remove some useless animations and effects from the windows interface in order to reduce the Idle RAM usage
go to system properties, performance and uncheck the most options you can!