Location of all the Add/Remove programs are stored.
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

TweakXP.com - "Windows Classic" themed logon dialog: "If you are using the Win 2k style logon prompt (not the Welcome screen) and want to change its default 'XP' style to the 'Classic' style, do this:
(Backup your registry before doing this, just in case you end having a problem.)
Open regedit, then navigate to: HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\ThemeManager
Change the value for DllName to:
%SystemRoot%\Resources\themes\Windows Classic.theme
Close regedit and log off to see the new logon window right away."

TweakXP.com - "Windows Classic" themed logon dialog: "If you are using the Win 2k style logon prompt (not the Welcome screen) and want to change its default 'XP' style to the 'Classic' style, do this:
(Backup your registry before doing this, just in case you end having a problem.)
Open regedit, then navigate to: HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\ThemeManager
Change the value for DllName to:
%SystemRoot%\Resources\themes\Windows Classic.theme
Close regedit and log off to see the new logon window right away."