To change the splash screen follow the instruction:

When WM5 starts up, there is a first screen that lasts about 18 seconds. We will change that second one.

Here is how.

Take a picture you would like there, and resize it into a 320 X 240, 24bit .png file. This can be done with MS Paint, Photoshop etc. Open the picture in Paint, resize it and Save As a .png with the 24bit color quality. Rename  the filename to welcomehead.96.png and just drop it in the /Windows directory. Use Activesync.