I wouldn't get too hung up on just what the 'PC' uses. You have to look at all the other peripherals and devices you are using while you're at your PC. My dual monitors (29" + 24", with brightness set to about 15%), modem/router, 8port ethernet switch and two 20Watt desk lamps account for over 150Watts.
If you really want to save power, you need to look toward a laptop. And sit in the dark.