PSP XI is *.psd format! why wouldn't it work? As a matter of fact it does what Photoshop does and more. By the way, I have your Legendary 727 paint kit which came out before your 707, same repaint format as your 707, and I'm able to paint on it.  Perhaps a separate paint kit for the 707 should be posted on your website, like you have for the Legendary 727, C130 and the MiG 21 ;)