It is certainly a good idea to do the floor before you move in, as you
won't have to worry about dirt and dust, nor moving furniture.

I would defer a decision until you have removed the carpet and padding,
so you will know if there are any problem areas that might affect your
decision.

My concern would be compatibility between the old finish and the new.
Amateurs usually don't have the knowledge to tell what the old finish
is, nor to be certain that the new finish will properly seal to the old.
As someone else said, having the floors professionally redone is not
too expensive, and perhaps you could even get a discounted rate because
the house is empty.

wrote:

My wife and I are moving into a house with beautiful hardwood floors
that have been hidden under shag carpet for years. The carpet and pad
appear to have left the wood it almost new condition (1950's)

I know fully refinishing hardwood is either expensive to have done
professionally and an enormous amount of work to do yourself. So, I am
looking for a simpler way to treat the floors prior to our move-in.

Is there a problem with simply applying a coat or two of modern
polyurethane to make sure the surface stays in great condition? If this
works, would I have to lightly sand the surface first or could I just
apply the polyurethane after a good cleaning?

I have not closed on the house yet, so I haven't' been able to test
the current surface for water absorption, wax, etc.

Thanks in advance for any help