Drivers and for some machines the app that controls things like Dell's Quickset. However some machines will never run 7 or beyond. You can research your model PC on the web or try adding more detail in your posts.
In short, I've never seem a Vista to 7 upgrade that didn't require me to go driver and app hunting.
I got my desktop with Vista. Paid for a legitimate (upgrade) copy of 7 Pro. Just want to make sure there won't be any snags.
I read at Forbes that we can register a copy of 10 before July 29, but don't have to use it. It mentioned that a few times, with no explanation. Sign in process is majorly malfunctioning there, so no opp to comment.

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