No, they wouldn't include the install DVD. This would be strictly for the code that lets you activate Windows.
As for the legitimacy of it... I'd be pretty wary myself. I'd say there's a better chance than not it's a scam.
A few days ago I was looking for another copy of Win 7 and checked eBay. There are several "keys' being sold there for $30-$50. It's unclear whether the keys include the Win 7 DVD.
In the word descriptions, the sellers claim the keys they are selling are from MS.
Anyone know if these are legal keys or is this some kind of eBay scam?