Another important detail, the early 2000s hit an important inflection point in computer design where compact machines were getting hot enough that you could no longer just eyeball fan, vent, & vane placement. You need someone experienced in heat transfer design, preferably equipped with professional simulation tools like Flotherm, to eliminate hotspots and ensure efficient flow. I can't prove anything without an engineer from the time leaking info, but the 360's guts look an awful lot like "just eyeball it" design, while the PS3 was clearly designed by someone who knew what they were doing. If they weren't using thermal analysis software, then they were just very, very experienced and clever.