We’ve had a quick play with the improved particle system in Blender 2.5, and we’ve found it much better with the new UI.
It’s 3 light meshes applied to one plane emitter with a vortex-collision empty in the way. Easy.
Click below for the 1920×1200 sized render, suitable for wallpaper. As usual, the .blend file is linked below, you’re free to do what you like with it.