Double post.
Yes, you can change the background.
No, about half the forum uses Windows and half uses Linux, but most of the Linux guys probably dual-boot Windows, and we all use GUIs, so I know what a wallpaper is.
Oh, you mean the screensaver.
Yeah, there will probably be a screensaver, and you can set it to display a picture of whatever.
Edit: I don't know what the hell you're talking about. You can set both the wallpaper and the screensaver, but the screensaver is the one that activates after you don't touch it for a few minutes, and it covers the other windows.
And what is your avatar? I want to comment on it, but I should probably ask who it is first.