Microsoft includes three default "shell styles" with the Windows XP Luna theme: Homestead, Metallic, and NormalColor.
You can see these three styles in the "Welcome to Windows" and "Log On to Windows" screens during logon.
Change the "ColorName" key value to either "Homestead" or "Metallic". "Homestead" will show the title bars in an olive color. "Metallic" will show them in a silver color.
Log off or reboot to see the change.
Note: this will only work on the original Ctrl+Alt+Del log on screen, not the new Welcome screen.