This should work fine.
My iMac has issues with installing or restoring a fresh install of the iPhone OS. It hangs at the last moments for like, 20 minutes, and I eventually have to just unplug the iPhone.
I installed a fresh iOS4 via my PowerBook G4 12". After it installed and was rebooting, i unplugged the iPhone 3G from the PBook and plugged it into my iMac. iTunes gave me the option to restore from the backup, and it worked flawlessly (it even carried over my carrier name from the jailbreak i had, so it says iPwn instead of AT&T, lol)