The information is in very general terms.
Just take care about the following issues:
1) If you crunch WCG full time your consumption will be higher. This because all the cores will be loaded and used 100%. You may modify that in the settings if you want. This does not happen when you use office software, were average CPU use is fairly low.
2) If you overclock your desktop, fairly easy with i7 series again consumption will be way higher.
3) If you crunch a Boinc project with GPU your consumption will be much higher and can go over 600 Watts.
4) I you play 3D games with a powerful GPU's same thing.

There are many things that can change the picture a lot. In short a dedicated hardcore cruncher will have a sizeable energy bill to pay, until purely optical computers become available, or we have supraconducting material at room temperature. Then we will have a fantastic reduction in our energy bill. But that is still a long very long way from home.