This report seems to suggest that the update errors are a server problem and have nothing to do with your iTunes or device.
Looks like all we can do is keep trying or just wait until later
http://www.businessinsider.com/updating-to-ios-5-2011-10
Looks like all we can do is keep trying or just wait until later
http://www.businessinsider.com/updating-to-ios-5-2011-10