Canon crippled that camera for windows users years ago by not providing drivers that worked in a 64 bit OS environment. Still to this day they have not updated these drivers despite most all Windows machines shipping with a 64 bit OS. I have a very old Windows laptop with a 32 bit OS and its the only computer I can shoot to with this camera.
I have a 1DsMKII and a 5Dii, but quite frankly I downsize 75% of these files prior to client delivery. There are times I would love to shoot the original 5d.
BTW, I also have Macs, and the camera works fine "sometimes" with the MBP. I don't take the MBP's on location much however. Most of my work is in dirty factories and a $700 windows laptop just makes more sense in that environment.