Not that I have heard of. At that stage your OS is loading and not loaded fully so the OS'es programs are not yet availible , so to make a boring long story short, no,nada,nyet. Borrow a camera like we did in the old days. I'm just sayin'.
A "Get around" would be to use a Virtual machine and while booting the Virtual machine press PRT SCR on the HOST computer (or use some capture software -- you'll have to be quick however).
Another tip -- look for some image file in Windows resources that looks like the boot screen -- might be a .bmp file.
Otherwise google on Windows Boot splash screen - you might get some info that way.
Easiest way to do this, would be to download "VirtualBox" (it's free), and install Windows 7 to it. You can screenshot from the host perspective, paste, crop and save it with photoshop/gimp/whatever.