Mail call:

Recently I have felt "limited" by some of the capabilities of (my digicam) system, and am seriously considering upgrading. The Canon Digital Rebel Xt (with the Canon kit lens 15 - 55?) (350D) looks like something that I can afford, but I am having a hard time picking a housing/port to suit.

The 350XT Rebel and housing is a great set up and is very affordable as the new 400xTi is coming online.

I'd recommend the 580EX strobe housing for Canon's strobe as a great option that includes TTL and in-camera control. The big advantage is that you also have an awesome topside strobe as well.

I sold a complete F350D setup to a lady in Canada and she likes it quite well, except for a few small things and the lack of an optical viewfinder in that housing.

"The housing itself is a joy - small, light, just enough positive buoyancy in salt water with the Canon 580EX in its housing to be no worries.
The three snaps are great, and I can even open and close all at once. The camera slides into the housing beautifully on its plastic base, no fiddling needed. I even found the little gap under the plate useful for stuffing silica (pouches) They also weren't needed - no moisture (from sweating) in the case - whoopie!" — Jennifer R, Ontario Canada

The good news is that Fantasea is greatly improving their housings for current models, like the 350 XT, the new 400 xTi and Nikon D50, D70 & new D80. They will have an embedded optical viewfinder, better port system, improved trigger/shutter control system and many more improvements. All come standard with a port and flood insurance. The standard Canon port fits the kit lens with zoom gear, but also the 60mm macro lens, which would be my first lens choice. The FD50N & FD70N housing with those features is currently in stock. The other housings are going to be available by early January. I'm promised a Nikon D80 housing and will do a no-BS review.

Bottom line advice? For whatever housing line you choose, I would buy a current camera and housing. You will enjoy all the new features and have a better return on your investment when you go to upgrade. The small difference in cost between a Canon 350XT and a 400xTi is well worth the features. The housings cost about the same for most cameras (around $849 on my site). I haven't seen pricing on the new 400 or Nikon D80 housings, but they tell me it's no more than a $50 or so increase.

OR, buy used. Enjoy the depreciation, use and learn the system, spend the extra money on lenses.