I can tell you that with your budget, I think you would be much better off going with the new Olympus 7070 (just released) and start with an Olympus or Ikelite housing. Later on, you can upgrade to a Light & motion housing if you really get into. There are major differences between the housings.
The Oly line of cameras has been the most successful camera (digicam) used underwater. They perform well in low light, the picture is sharp, you have a lot of control over the camera, and there are plenty of accessories available for all of the housings. There are also a lot of u/w shooters with the Oly line, so there are plenty of knowledgeable people to help you out. I have shooting with and teaching with the C-series line for 4 years (starting with the 3030) and I have never been disatisfied and either have any of my customers.
Let me know if you have any questions or if there is anything I can do to help.