I bought a Captivate to sell, it had a custom ROM that was missing the kernel when I factory reset it.
Was able to do Download mode the correct way (volume up + down and insert USB cable) the first time, tried using an all-in-one Odin flasher off some other lame site, and it pretty much bricked it up. Wasn't able to use the normal Download mode method, but after running across this thread whilst doing some Googling, I ran to RadioShack and created a new tool =D
The silicone sucked getting out from between the wires, but other than that, it worked like a CHARM!
Thank you so much!!!