If you have Windows 7 ~

[grave_digga]

Maybe the administrator has set a password? Try administrator:password, maybe that works. But you don't really need that, on every *.exe or *.bat (executables) there's the right click option "run as administrator" as bFeared mentioned above.

[R00k]

I get error 5 for this "net user administrator /active:yes"

[bFeared]

Now that is something I didn't know. Neat. I'll just keep right clicking everything to press 'Run as Administrator', though.

[foq]

save this is a .bat and run

@echo off
echo this will enable the administrator account
pause
echo you may need to run this tool as administrator
pause
net user administrator /active:yes
pause

It enables the hidden adminstrator account... should absolve any issues with Windows 7 denying you access.

[bFeared]

Old news, bro.
It is a neat effect, though I don't use it. Too slow and I use the old windows theme anyways.

Random non-sense:
Hovering over the bottom right (top right for me) of your taskbar will 'hide' all the windows.

[Mindf!3ldzX]

This post is to be filled with random/useful nonsense about Windows7, YAY!!

1)Hold WindowsKEY & Press TAB. Does a 3D perspective scrolling between open windows, and it's just a overall fun neat effect !!!