I don't see a 1080p video playing very well on a 1600x900 display. Look to 720p video tests on YouTube. This image should be crystal clear, but not taking up the full screen on the laptop monitor.
Assuming that you're looking at the cheapest of the Inspiron 17R edition
, then the included GT650m should be more than enough to handle any HD video.
I would search online for terms like "Video Upconversion" for your graphics card/laptop to make sure you're getting the best images possible.