For 24x36 prints, the 11 megapixel 1Ds is barely adequate. You need really good glass (primes or L zooms only, consumer-grade coke bottles need not apply) and must get the composition right in-camera so that no cropping is necessary, and even then the print isn't going to have the crispness of a 12x18. A 10D simply isn't going to cut the mustard, nor will a 20D or even a 1D-MkII, which I happen to own. The 1D-MkII makes a good 20x30, but that's as large as I go with 8MP. If you really want good 24x36 prints, you can't screw around with the cheap stuff, you need at least 11MP and top-notch lenses or you're wasting your time.