In this post I describe how to create a custom design for your installer. To get your setup program a modern view you may use your company's logo on it.
Like that:
How to do this?
Actual Installer uses a wizard bitmap from folder
C:\Program Files (x86)\Actual Installer\Bitmaps\Wizard
The size is 500x314 px:

That's it!
Have any questions, comment it and I'll try to answer it.