This instructable is something I did a long time ago when I was in college to make my Windows 95 desktop look more cool than that of my friends.
Forgive me if the wallpaper is a measly 800 x 600 but I hope you are able to create your own HI Res ones after going through this.
You can see what the wallpaper effect looks like in the video below
The effect looks like as though signals are passing through the circuit of the motherboard in the wallapaper in tune with the songs playing in Winamp.
Winamp + Advanced visualization Studio vis plugin (installed by default)
The attached wallpaper (download the zip file)
This instructable is best understood by doing it yourself first only then will it be easier to understand what I am trying to do, later you can use your own images the way you want.