Make sure that you've installed the latest version of iTunes on your computer and make sure it's on the latest version of the operating system. In addition, disable or turn off any security and anti virus software. Try the restore again and let us know if it works.
I downloaded iTunes for Windows today, so it should be the latest I guess.
I did a run a Windows 7 OS. I guess it has the updates, it surprises me that this could be a problem. Anything specific to look after?
Disabling anti virus software is worth to check out, pretty common that a anti virus software is running on Windows.
Is it in general more easy to fix this with a MAC or should a Windows PC also be good enough?