I've had the opportunity to give advice on this issue a few times - here's the best advice I can give with the experience I've had with my 4 cameras:
1) Choose a company for which cameras are their main priority - Nikon, Canon, Minolta, Kodak, etc.
2) Choose optical zoom over digital zoom. In other words, a camera with 10X digital zoom is not as good as a camera with 5 or 6 times optical zoom. Optical zoom means the lens actually moves and changes the image that is received on the CCD. Digital zoom means a chip inside the camera guesses at what the picture would look like if you could actually zoom in. The real thing is always better than a guess.
3) Know your intended use - don't get a 6 megapixel camera if you're only going to use it for the web, for jobsite progress photos, or for pre-sales meetings. You only need 2 Megapixels for that.
Do get a high resolution camera if you intend on making good sized prints from your 'after' photos, either for a portfolio, or for blow-up pics for trade shows, etc.
4) Buy the extended warranty. I never, ever, ever do this. But I had a moment of weakness when I bought my most recent camera (which gets almost daily use), and it has already paid for itself - I got dust in the moving parts and it gummed everything up. They just gave me a new camera.
5) After the pruchase, invest in high speed memory cards and the new 1-use batteries made just for digital cams. These two things will greatly reduce your cycle time between shots and ensure that you don't run out of juice just as you're taking the important shots. Expect to pay triple (or higher) the usual cost for the batteries, and 1.5 - 2X the cost for the memory. But they are both worth it.
If I have to name a brand - I've been happy with my Nikon CoolPix. The name sounds like a kiddie camera, but it's extremely fast, small, durable...everything I want in a daily-use cam. But there are other equally good cams for the same money.
If you are looking to spend $400, spend $300 and put the rest on high speed memory cards (with a lot of memory) and good batteries.