It's my sisters dog called Amy. I took that photo in April 2004 (she's a lot bigger now), put it through Photoshop and have been using it as the background ever since.
It's designed for my Win2K, so it's originaly 8bit BMP. The left bar is for icons
... I also have altered windows colors to some little-blue-darker-gray to reflect the image colors.
Here is the original BMP version: [link]