That's a tough one. The best measure is to simply test and see if you can notice the difference, if at all possible.
Be sure to use the same make/model of TV when comparing, otherwise it may just be the differences in TV's you notice, if you notice any difference at all.
What I did was I went to a local Futureshop and asked to compare a blu-ray on two TV's as I've described above (52"). I noticed the difference, and to me, it seemed substantially different.
But on the otherhand, many will say that the difference isn't especially notable when not compared side-by-side.
So, I dunno. I'd suggest, if you have the expendable funds and don't mind spend it on the 1080p, if and only if there is a noticable enough (for you) difference between the two in-store.
Haha... I'm not sure if that'll help at all, sorry.







