In Mandrake v9.0 using the KDE... they (someone) mapped the windows key, the one between control and alt, on the left side of the keyboard as the F13 key.
I find this humorous, others may not see the humor in this at all.
So when you hit the ctrl+windows key combo while logged onto KDE, the main menu opens up on the screen near the mouse pointer, usually on the lower left side. This function can come in very handy at times!
Or to put it another way, when you see ctrl+F13 in a forum somewhere you will have a clue as to what the hell they are talking about.
Usually this function is mapped to the ctrl+F1 key combo in the KDE.