As to the body: I'd go either Canon or Nikon. Both have huge lens selections, and the third party manufacturers make lenses for these mounts first, so you get the best of that world too. The 400D is a very capable camera. I nearly got one, but I wanted the size and feel, plus faster and more accessable control, so I got the 30D, but the 400D has pretty much everything you'd need for several different types of shooting. On the Nikon side, the D80 or D70s if you can find one would be fantastic. The D50 isn't too bad either, though it has fewer features.
I also wanted to jump in real quick in defense of the Sigma 18-125, which has been taking a beating in this thread.
Just so you know...it's a surprisingly good lens. It's a bit soft wide open, but I've still made quite nice prints at 8x12 wide open. It's quite sharp stopped down a stop or two, and it has a fantastic range. I'm not saying it's perfect...it's got a lot of barrel distortion at the wide end, it's slow, it's a little softer at the tele end, and it's not as contrasty as better lenses, but it's still a very nice lens for the price. I'll be replacing it with an f/2.8 standard zoom soon, but it's still a good lens.
Now, if you can afford a better standard zoom like the 17-55 IS or the Tamron 17-50 f/2.8, go that route, as they are better optically, but if you're on a budget, the Siggy is a great starter lens.
), etc. Seems like you've reached a pretty good level and jumping all at once might be a bit of a creative shock. You could get a replacement film camera then maybe a cheaper digital, like Nikon D50 or D70 - or even used Canon 20D (saw one for $600, that's what, $400 Euros?). Even the digital Pentax is decent - maybe not the wedding photographer's first choice, but decent.




