How much electricity do computers use ?

Computers
Desktop Computer	60-250 watts
On screen saver	60-250 watts (no difference)
Sleep / standby	1 -6 watts
Laptop	15-45 watts

Monitors consume  more than 70 % of the energy consumed by the whole computer unit, so its advisable to switch off the monitor when you are just listening to a playlist, or when u r just downloading something.

Screen Savers save nothing. Use sleep/standby/hibernation.