Be warned, for what it is worth, when I built my new computer about six months ago, I got it completely running, XP updated, virus protection installed and all software working as I wanted, then I downloaded and installed the latest iTunes. It worked beautifully - except that it completely refused to update my iPod.
Fortunately there is an Apple shop in my local shopping centre and they were very helpful. I was advised to download another copy of the install file for iTunes, download same for my virus protector (Avast) then delete iTunes and Avast from my computor after disconnecting same from the internet. iTunes should then be reinstalled followed by Avast. Then reconnect to t'internet an ensure Avast was fully updated. Guess what - it worked and I can now do things with my iPod again.
P.P.