Hi,
If you have been using Vista and enjoyed it, you will find it very familiar.
Depending on your needs and equipment , you might not notice all that much difference.
Probably worth installing RC7100 even if just for a while - to see if you think it's worth it. T
That will be Ultimate though, and don't forget it will be a clean install , so will seem snappier than something you have had installed a while.
There also won't be any manufacturer bloatware on a clean install - you may well have a ton of that junk if you currently have a pre installed Vista.
Be careful to take that into account - many don't.
I think it's worth it for $50.