Well i am going to disagree with the last 2 posters and say NO,you will not notice any improvement.
I am basing this on the DVD player you are currently using,and the tv you are using it with...which you intend to keep,because you never said otherwise.
You can better the DV79,although you will need to be prepared to spend a significant amount of money to do so,but unless you also change your tv,then i think you will be wasting your money.
You already have a superb DVD(and CD)player in the Arcam DV79,and the fact that it cannot upscale does not matter,because your tv does this anyway.
So as long as your DV79 is in perfect working order,i would stick with it,at least until you are upgrading your tv.