With the release of iOS 5 for iPhone 4, 3GS, iPad, iPad 2, and iPod Touch 4G/3G, iTunes is now updated to version 10.5 to support several new features including iCloud and Wi-Fi syncing of iDevices with iTunes.
iCloud is a free service provided by Apple that lets you keep your purchased TV episodes and music on the cloud (on a remote Apple server) and push them to all your iDevices.
What’s more, you can now automatically download your purchased music to any of your iDevices and your PC or Mac as well. Purchases you have made prior to the 10.5 update can also be downloaded free of cost as long as they are available on the iTunes store.
If you are upgrading you iPhone, iPad, or iPod Touch to iOS 5, then make sure that you first update iTunes to the latest version. You can update iTunes on your PC by going to Help –> Check for updates.
Or you could download a copy of iTunes 10.5 from the below direct download links.
Download iTunes 10.5 for Windows 64 Bit (Windows Vista or Windows 7)
Download iTunes 10.5 for Windows 32 Bit (Windows XP Service Pack 2 or later, 32-bit editions of Windows Vista, or 32-bit editions of Windows 7)
Download iTunes 10.5 for Mac OS X (DMG file – Mac OS X version 10.5 or later)