can't find my IPSW files

[tommyjw]

When I perform a backup of my iPhone 3G, I would expect to search my hard drive (Windows XP) for an IPSW file. I find a very small (36K) *recovery.ipsw file in my \iTunes\DeviceSupport but theres no way it's holding the contents of my iPhone. In my \Application Data\Apple Computer\MobileSync\Backup folder, I just see folders with a GUID naming convention and under them, files with the same naming conventions.

I guess I don't understand the difference between the GUID file names and the ipsw files. Can someone help?

p.s. I want to jailbreak but want to make sure my iPhone is properly backed up before I do and would love to copy the ipsw (if it existed) to a DVD.

Thanks.