iPhone 4 wont update to 4.3.1. Stuck in DFU at moment unable to use.

Hi,
Today I plugged my iPhone into the computer, and iTunes said their was an update, 4.3.1, from what I was already running, 4.3. I downloaded the software but it said it was corrupted. I tried this three more times on two computers, both running the latest iTunes and Windows Seven, and even disabled antivirus, firewall etc. with the same result.
I then tried downloading the update directly from another source, and this time, I received error 14, on both computers again. I have restarted computers, reinstalled iTunes and all cooperating Apple programs, changed cables but nothing seems to be reviving my iPhone 4.
I need someone to help me fix this or reassurance that I will not be left with a bricked iPhone through no fault of my own.
iPhone 4 iOS 4