I know this is a one month bump, but this section doesn't get a lot of activity at the moment, and this topic is relevant to my post. =)
I have an Xenon with a 20GB HDD, three USBs (one 10GB, one 7GB, and another 10GB) that I use interchangeably, and a 2TB external hard drive.
X clamps are removed, never had RRoD, 12v fan mod, and I just recently changed my mind about keeping the case on, took the thing apart, and I blow a high speed fan directly on the CPU/GPU when I play.
It never goes above 40 degrees. =)