This may be a silly question but... I have been searching for a camera with a bigger sensor. My current lenses were bought specifically for a 35 mm camera and I am very happy with them on a 35mm! Not so happy with them on the APS-C size sensors however. I have tried to make due with these for a few years now and I just really miss my 24mm and my 20-35L on my A2. I also miss the view finder you get with the 35mm format. I just haven't been able to find any of the 10-20mm varieties of lenses that suit my fancy as I really prefer the 2.8 wide aperture that I get with my 20-35. With all that in mind I have been seriously considering the new 5D MKII but the cost is a bit higher tahn i would really like. The 1d mk III is coming down in price and to me seems like it would be a bit better for 700 dollars less. I dont really need the 21mp, they would be nice, my wife likes to print things the size of my walls! The 1.3 crop factor of the 1d doesn't put me in a whole lot better position than puting a 17-50 2.8 on a 1.6x body though. the 1ds is just a bit out of my price range still. All that said, does any one know if i could expect 5D to be compatible with newer computers and operating systems? I was considering the 1d and 1ds but have noticed that some people are having a hard time, with the 1d at least, on vista. That would make me think that there is a possibility that I could have the same problem in a few years with another older camera such as a 5D and my old 10D if i were to upgrade operating systems in the next few years. IF i were to buy a 5D could i expect it to be useable for 5-6 more years! or would i be better off with a MK II, would the 1d mk III be better in this regard?