Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_0 like Mac OS X; en-us) AppleWebKit/532.9 (KHTML, like Gecko) Version/4.0.5 Mobile/8A274b Safari/6531.22.7)
The 4.0 backups have nothing to do with your iTunes version. As long as you have the SDK installed it'll backup. So that means no backing up for Windows.