OK, Got the iPad 2 all updated to 5.0.1. But in trying to update the iPhone 4S, twice I've gotten the following message: "The iPhone 'Rob's iPhone' could not be updated because the firmware file is not compatible."
First make sure it's the 4S version. Then try these suggestions:
1. Do a hard reset on the phone and reboot the computer.
2. Temporarily disable your antivirus.
3. If the above suggestions don't work, just update to 5.0.1 on the phone rather than the computer. It's a faster process and doesn't require downloading the entire firmware file.
Settings > General > Software Update