I find this: "that can't play fullscreen video" quite strange. I have no problems with fullscreen videos (~5% cpu), or multiple windowed ones on a 5yo cheapest unknown-local-company laptop. Are you sure your configuration is not broken in some crazy way?
Not saying that you shouldn't update, but this is not what a 5yo laptop of any kind should behave like... If you do the same thing to your new laptop, it might not be worth getting it ;)
"Fullscreen video" isn't saying much. Sure, my 5 year old AMD64 desktop can play fullscreen video. Can it play fullscreen 1080p h.264 / HD Flash (remember, 5 year old video card == no HW acceleration) without dropping frames or turning into a space heater? Not so much.
Not saying that you shouldn't update, but this is not what a 5yo laptop of any kind should behave like... If you do the same thing to your new laptop, it might not be worth getting it ;)