Looking at the wonderful bootscreen of a DEC PWS 433 during BIOS boot phase, I had the idea to preserve this image. Looking around for the image file, I wasn't successful.
So I made a picture with my Nikon and cropped & scaled for Win7 Boot Updater, see
http://www.coderforlife.com/projects/win7boot/
Download the program (no installation required), and choose "complete" for the background picture:

You do not have to choose other options (let the animated windows logo as is).
And here's the background image file itself you have to choose:


Happy DEC PWS booting...