Where does the progress bar freeze? on which part of the process.
You might need to either delete the downloaded os5 ipsw file which prompts itunes to redownload. goto c:/users/**your username**/app data/roaming/apple computer/itunes/software update and there will be a file that ends with the word "restore" you can delete that no issues.
Or you might need to put your phone in DFU mode. turn the phone off and plug it into itunes.
Hold both the power and the home button on the front of the phone for EXACTLY 10seconds, after 10seconds let go of the power button and hold only the home button for EXACTLY 10seconds, itunes should install some new drivers and pop up saying a phone in dfu mode has been detected, then restore the phone again.
If the progress bar is getting stuck when trying the verify the download then could be your firewall blocking itunes.
PM me if non of the above work (i will get an email then) and i can tell you more todo. Over the past 3days i have resolved so many of these issues my head hurts!