With a 50" TV 1080P would be noticeably better PQ from closer watching distances like 4-8' away, if you are farther away than that you wouldn't see much bifference.

You would still enjoy Blu Ray or the higher def gaming consoles at 720P, it is much easier on the eyes and looks cleaner crisper than 480i/p, just like your TV box output is 1080i or 720P is just that much nicer to look at than standard definition 480i.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70