I pretty much agree with Craig.
If you are not in a hurry, I think your options will be greater and cheaper in a couple of months.
1) For some reason, Fuji is resisting the price decreases. The 10d is $1500. The D100 is now $1700. The S2 is hanging tough at $2200, but it seems like it must drop to stay competitive.
2) Aquatica should have their S2 housing ready by mid-summer. Ikelite should have a new S2 back by mid-summer, also. The Aquatica will be a smaller foot print aluminum housing with full controls and better port/lens offerings. It's the same price as the Sea & Sea box and the ports are cheaper.
The S2 offers TTL and arguably the highest effective resolution of the three. The D100 offers the best housing selection and broader third party software support.
TTL is a distinct advantage. I could argue the resolution a little bit, but I won't. Truth is I prefer the S2 "out of camera" color and resolution, even if the pixel count really isn't any different. The D100 has a bunch of other little advantages that don't matter underwater.
For wide angle lenses, the current choices are the fisheyes, the 14mm and the 17-35 zoom. Shortly Nikon will begin shipping the 12-24 DX zoom that may become a very desirable choice. Until then, I like the fisheyes. They're half the price, size and weight of the 14mm and offer very good performance with the S2/D100.
The 12-24mm will be the best choice. It's new and just hitting the shelves. In a couple of months it should be readily available. I've been using the 17-35mm, which I love. I'm now a convert to the WA zoom. Much easier to compose. The 14mm is expensive and wide (=21mm full frame). While "everyone" will tell you that 20mm is the magic wide angle used underwater, I find it too wide, too often. That's why I really like the zoom approach. If you can't wait or afford the 12-24mm, look at 18-35mm. It is much cheaper and any loss in quality is negated by the crop factor of the S2. I still find the fisheye a "special purpose" lens, even with the crop. It would not be my first choice or only choice for wide angle.
For macro the lens to start with is the 60mm micro with a flat port. If and when you grow out the 60mm, you can consider adding the 105mm or you could consider the 70-180 zoom micro. Aquatica, Nexus and Subal offer ports for it now. It is large, heavy and expensive for a lens to start out with and it has become hard to obtain.
Agreed. The 60mm is the most versatile. It's the cheapest. It autofocuses the best. It requires no port extensions. Shoot it until you decide you can't get all the shots you want, then add something else. With strobes on TTL, aperture priority, f/22, you now have a "point and shoot" autofocus camera. This allows you to concentrate on 1) finding the subject 2) best way to approach a subject 3) best angle to shoot the subject 4) overall composition 5) strobe aim. No messing with camera controls.
An SLR viewfinder is infinitely easier to use than an LCD in my opinion.
My Aquatica D100 housing review is a couple of HTML tags from completion.