With the release of Windows 7 SP1, Microsoft has also updated the Windows 7 DVD media ISO image distributed by Digital River for online order fulfillment. Digital River is Microsoft’s partner for fulfillment on online distribution for downloadable Microsoft products.
The Windows 7 ISO images hosted on Digital River is genuine and official version, and the downloads from the server is legal. It’s after all one of the official channel where end-users who purchase a license (product key) for Windows 7 get the setup installation files.
Anyway, without a genuine and legally purchased product key, you can’t get Windows 7 activated, and Windows 7 will only run as evaluation copy for up to 30 days.
The latest version of Windows 7 DVD image available is of media refresh version, which commonly known as Windows 7 SP1-U (Media Refresh). Microsoft released the media refresh version of Windows 7 DVD media to fix a rare bug related to invalid computer name when small set of computer names returned error when used to install Windows 7. Otherwise, the Windows 7 with SP1 and Windows 7 with SP1-U (Media Refresh) is completely the same.