Windows 7 - Change Login Screen

Reference and Credit - http://www.tomshardware.com/forum/52395-63-change-windows-splash-screen-lock-screen

click start type regedit and hit enter
right click on HKEY_LOCAL_MACHINE and select find 
type OEMBackground and hit enter
(the path should be Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI\Background )
(if it is not there you need to create it*right click on background and select new DWORD name it OEMBackground set it from 0 to 1)
double left click on OEMBackground and change the value from 0 to 1
click start and type %windir%\system32\oobe
in the oobe folder create a folder named info
in that folder create a folder named backgrounds

now rename your picture that you want displayed durning logon/lock screen backgroundDefault.jpg

everything is case sensitive so if you have to copy and paste the names. the picture needs to be under 244kb.

trick to get a picture under the 244kb
right click on the picture and select open with > select paint
press ctrl+w
this will bring up a box under horizontal and vertical select the amount you want to reduce the picture in %

=)