Windows 7 is now available on MSDN. Is this time limited in that you will need to reinstall when Windows 7 is released to the world in a few months? Or will it just need an updated key, or need nothing at all?
The Windows 7 out on MSDN is the RTM, or Release To Manufacturing, build. Meaning that what is on MSDN is the same thing that's being pressed on to DVDs in factories right now, ready for the launch in a few months.
In other words, you're already running the full product and you won't need to do anything when MS start selling it in the shops.