Sooner is right, it is Vista, it's just a slimmed down version of Vista. Vista is a resource hog and is frankly just annoying with all it's pop ups asking you if you want to actually launch this program, "Well, I clicked on it so I must want to!"
I understand the purpose of the UAC (User Account Control) but it really should be smart enough to see the difference between the user launching an app vs. a piece of spyware or a virus launching an app. It's so annoying that I turn UAC off first thing when working on a Vista machine. This of course defeats the whole purpose of UAC but it's one of the first things done by most people.
Essentially, Windows 7 will hopefully just be a more user-friendly Vista for the normal end user. Vista has had a bad rap from the get-go and changing the name and tweaking it will probably help Microsoft's sales, it would be nice for them to offer a free upgrade option to those who have machines running Vista but it is Microsoft we're talking about and they don't like giving things away for free.