VGA connector

Hi

I have recently developed interest in photography. Currently I am using a dell Inspiron 1440 laptop with duo core processor and 4 GB memory. I use Lightroom 4 for processing RAW files from D5100. It is not very fast but OK for me because I don't have a lot of photographs to work with.

I am not happy with laptop screen because of poor viewing angles and plan to buy  Dell ultrasharp 2412m monitor to use with laptop. My laptop does not have HDMI or DVI port, just a VGA port. My question is how much degradation in image quality I will see as compared to a digital port? Is it worthwhile or should I start thinking of upgrading my laptop instead.

Opinions and help will be appreciated.