L3m0n_L1m3 said:
Horizontal, since it (my fat PS3, mind you) is placed in my TV stand.
I vote vertical, because when put it in my TV stand (thus, horizontally) I find that both the PS3 and 360 get much, much, MUCH hotter in an enclosed space than they do out in the open. Seeing as how I've had both systems for 3+ years and never had any hardware failure (which is a big deal, considering the frequency of RROD), I think vertical and out in the open - and thus cooler - is better.
CoverYourHead said:
I keep both my PS3 and Xbox 360 on their sides, but it's more about the fact that I have them on carpet and they tend to lean precariously if I put them vertically.
Not to be an electronics nazi, but you might want to avoid keeping these systems on the floor, lest they clog with dust and overheat. I've seen it happen too many times - just a word of warning!