Create backup of my current ROM

[Johnny.Bravo]

Thanks for the info. I finally got Clockworkmod Recovery installed today (after several tries). So once I create the backup, where is that backup image, and can I store it on my PC in case I lose my phone and have to get a replacement? Is it a .zip or .rar or .iso or something like that? Or is it only stored on my SD card? I was hoping there was a way to do this using Odin so if anything really bad happens I can just do what I have done several times already, only instead of flashing my phone back to stock, I want to flash it to my saved ROM. That way I won't have to go through all the pain of rooting the phone and installing CWM again.