French company DxO labs recently made public their test findings on some of the most popular low to mid range DSLR cameras. The results were quite surprising and Sony must be pleased with what they found.
Keep in mind that DxO uses their own special measurement system, and that they were only comparing statistics on the sensors. Their results show that the sensor in the Sony A700 is better then the Canon 40D and 50D, and almost ties with the Pentax K10D and Nikon D300.
While their results are interesting in a sort of academic way, they may or may not reflect real world results. My advice is as always to choose the best camera you can afford, and make sure it’s something that you are willing to carry around with you. No matter how fancy a camera you buy, if it’s sitting it the bag at home it’s not taking pictures.