Odd win 7 thing i just found

If you are at the welcome screen for Win 7, and it has two users (the last user and a "other user"), if you push Alt + any other button, the w in swith user is underlined. What does this mean?

sorry for the spelling

I believe that is for keyboard use. Same as if you were in, say, a browser window. Pressing Alt will highlight the menu bar, and you'll see certain characters underlined (F for File, E for Edit, etc.)

Why is that needed?

A secondary option, I would say. Some people may even use that method as an alternative to moving and clicking a mouse, depending on their habits. I've also had occasions where I've worked on a computer with no mouse, and had to navigate using the keyboard. It is possible to do alot with just a keyboard. The trick is knowing the shortcut keys. That's what that highlighted W means when Alt is pressed. Pressing W should take you to the Switch user option, or at least highlight it.