In respect to flash, the D40 sync up to 1/4000th with off camera flash. The SB-600 won’t let you sycn past 1/500 and do its computer tricks. Just adjust the shutter speed to 1/500th and fire away. The 600 will do the rest.We can shoot at very high ISO to advoid camera shake, and use the current software to produce wonderfull noice free results. Compared to ten years ago, every modern DSLR produces better results than the best film cameras. That includes the D40. And the D40 has real advavtage if you plane to use flash.