Currently Being ModeratedMar 11, 2012 12:54 AM (in response to A_JEDHE)
If you already have iOS 5+ on your iPad then you should able to download it directly on the iPad via Settings > General > Software Update (which will just download what needs updating as opposed to downloading it on your computer which will download the complete iOS).
If temporarily turning off all your firewall and antivirus software until the download has completed doesn't work, then you could try downloading the update via a browser and then in iTunes press and hold the shift key on Windows (command key on Mac) when clicking the Check For Updates button which should let you navigate to the downloaded file :
Edit : links corrected
Message was edited by: King_Penguin
Currently Being ModeratedMar 11, 2012 8:11 AM (in response to A_JEDHE)
What iOS version is currently installed? If iOS 5.0.1, you can update to 5.1 via wifi (not connected to your computer).
iTunes: Specific update-and-restore error messages and advanced troubleshooting
Currently Being ModeratedMar 11, 2012 8:16 AM (in response to A_JEDHE)
Will the current update be downloaded automatically to the iPad? I'm going to quit trying to manually do it if so.
Currently Being ModeratedMar 11, 2012 8:23 AM (in response to Anchann)
If will only be downloaded directly on the iPad if you tell it to via Settings > General > Software Update (which is only possible if you are already on iOS 5+). If you are downloading the update via your computer then you should be prompter to download it when you connect the iPad to your computer's iTunes - if you aren't prompted then you can click the Check For Updates button on the Summary window on the right-hand side of you computer's iTunes when you've selected the iPad on the left-hand side