This is my second 2011 13" MBP in a week. I returned the first one, a 2.7/i7 running on Lion, to Apple for serious fan throttling issue due to heat I have never experienced in my old 13" UMPB 2.4 c2d. I was registering 5800 RPMs and 80*C for a simple YouTube video or Time Machine backup with nothing else open. This second unit, a 2.3/i5 I bought, has same issue with the first machine. Fan revs up to 5000-5800 RPM at 70s to 80s Celsius temp for simple non-gaming, non-video/photo editing apps. I bought a Snow Leopard CD to try to erase the hard drive by pressing "C" to force it to boot from the CD and install 10.6 but apparently pressing C with Lion on a partition is not going to work anymore. Pressing Alt/Option key to bring up Disk Utility and erase the drive will also not work as the disk "cannot be unmounted." I tried Alt/Option and restore from a Time Machine backup. Luckily I have plenty of dates to choose from both 10.6 and 10.7. Voila! After successfully installing Snow Leopard, I ran the same video streaming sites on multiple tabs while time machine backup is running in the background, mail is also running in the background, and browsing shopping sites and I didn't encounter the "over heating" anymore, just like my trusty 2010 2.4 c2D. An Apple customer rep I spoke to gave me a lengthy lecture about how Snow Leopard will not run on this machine and is not intended to. The guy was a complete idiot--didn't know what he was talking about. Early 2011 MBPs shipped with Snow Leopard with Lion as free upgrade.