u can replace them or make ur own , C:\Program Files\Adobe\Adobe Photoshop CS5 (64 Bit) , scroll down and open PSArt.dll , with restorator , and locate splashbackground and its got to be named SPLASHBACKGROUND.PNG ,the image u make , of course
or extract the original 1 an give it a gradient whatever , make sure photoshop is closed off tho when changin the images