iTunes won't download for Windows!

I am trying to download iTunes 11.0.04 on my Windows 7 32 bit. I try to do it from the Apple Updates thing on my start menu and it says it has and invalid signature. I go to the website and it says "thank you for downloading iTunes," but it never downloads😢! The same thing happens on my Windows Vista and Windows 7 64 bit. What do I do to download it😕? I need it to sync my music onto my iPod touch.