I had also narrowed my choices down to the Olympus E-Volt E-550 and the Canon Digital Rebel XT. I decided on the Olympus for a few reasons:
Image quality:
CCD, dust reduction, and a larger/crisper LCD display.
Ergonomics:
I didn't like the index-finger dial control on the Canon - thumb dial on the Olympus is more comfortable. The Olympus also has a more ''grippy'' surface (plastic-bodied SLR's are front-heavy).
Multiple memory slots:
If I'm taking a long trip, I can pull the 2GB compact flash card out of my digital audio mixer and never even consider the possibility of running out of space.
The deal-maker:
For me the clincher was actually my previous film SLR - an Olympus OM-10. By purchasing a relatively cheap converter ring, I can use two of my old lenses while saving up for their pricy digital equivalents. Of course, things like auto focus don't work via a converter, but I didn't buy it for auto settings.
Complaints:
My only complaint so far is with the full-auto mode. In low light, the fill flash fires repeatedly before it finally takes the shot - IF it takes the shot - sometimes it simply refuses. Again, I didn't buy it for auto mode, but it shouldn't refuse to take a picture.
Refusal-to-shoot hasn't been an issue when I've tried the scene-auto modes. (And there are a lot of them - standards like portrait and action, plus very specific modes like documents and fireworks.)