The 40D is an excellent camera for both land and underwater work. There are also some great prices to be had right now. This camera has loads of room for learning and trying new things, so if cash is anything of an issue, I'd simply head for the 40D over the 50D.

The 50D is a hot little unit and if you have the cash you might want to splash out, but I am not changing from the 40D Some of the new features on the 50D are lovely, but nothing that I can't live without as a 40D owner already. Also, there will be a wait for housings on the 50D as it has just come out.

There are several choices of housings for the 40D as it's been out over a year now and you may also find that there are some people who will be moving to one of the newer models so selling their 40D housings (though rumor has it the 50D actually fits, so maybe not the exodus past model releases have caused).

You can't go wrong with either of these models at all.

If you are going to head to a housing, remember that there is more to the overall cost than just the housing...you have ports, strobes, synch cords, zoom gears, extra insurance, more bulk and weight in travel...

Whatever you choose, it's a great birthday pressie, for sure!