I don't subscribe to the notion that you can buy too much camera in the first instance. I've advised loads of people on cameras over the years and I'd always say buy the one you're not going to outgrow in 5 minutes. They're all basically the same light tight box, but some have more features than others.
All the cameras you mention are different horses for different courses though, and I think you need to slow down a bit, and not go buying on a knee jerk reaction. Yoir ideal choice totally depends on the sort of photography you want to do. You really can't compare cameras like the 50D and 1DS models, they're as diffferent as chalk and cheese and both excel in different areas.
Do a bit of reading around the board, there are loads of threads on the subject.