In joining the rest of the eco geeks in contributing small or little ways to help the environment I switched to a black background for my desktop for a start and sharing a few steps here.

I explored a bit on having other things (windows content, application backgrounds) to black but not ready for that transition yet.

Nevertheless I just figured for a few of those out there who wish to change to a back background but not quite sure how. (** Warning: this may appear too simple for some so this is not intended for you)

1. Click on your desktop background. You should see a menu item named Properties. You should something similar to this: (Note that the My Computer icon is only included to illustrate that this is done by clickin on your desktop background - eg. in the image anywhere in the backscreen/space) 

2. Click Properties menu item and you should see something similar to the window in the image below. Then click on the Desktop tab

3. While in the desktop tab, find the color drop down in the lower right corner. Select your background color (eg. Black)

4. Click Apply, wait for the changes to be applied, and click OK

Will also include my Black theme file here. So here too are the steps for using a custom theme file. (I think you can add this file in a theme folder and it will appear in the themes list but going for another approach for now).

1. Download My Black.Theme (5.42 kb) and save it on your disk (eg. C:\)

2. Show Display properties again (see item 1 above) then instead of going the desktop tab, stay on Themes tab. Note the Theme dropdown list highlighted in image below.

3. Click on the dropdown list and you should see a browse option at the bottom of the list. Click on it. It will open a File Select Dialog and from there look for the Black.Theme you saved on your disk in item 1 above (eg. in C:\). Click OK

4. At this point Black should be the item selected in the Theme dropdown list.

5. Click Apply, wait for the changes, then click OK.

They say the effects are significant for CRT monitors vs LCDs but even if you're using LCD the small difference is significant if combined together. Besides what's there too loose, the black backgrounds doesn't hurt and looks cool anyway. :)