Camera Recommendation?

Hi

I'm in the UK and want to buy a good quality pro or semi-pro digital camera to take shots for a mail order catalogue and or flyers but don't really know where to start, can anyone help with some advice?

I've been looking at the Canon EOS400D which is 10.1 megapixel, but does it have to be as high as this, and is this a professional camera or nowhere near? I'm looking at still life shots so shutter speed doesn't need to be super fast. High quality printed photos up to 15 inches high and clear colours are most important. I also want to be able to take good close-up shots without loss of quality.

Any recommendations will be greatly appreciated. Does anyone else do photography work for mail order companies and could recommend what other equipment I'll need? I'm just starting out with this and the only other thing I have so far is a tripod so any advice would be greatly appreciated.

Thanks,
Cameron