They're really inconsistent about the "turn on the laptop" practice. I've been traveling in and out of the US, and they only occasionally ask inside the US. Traveling around Europe, no one has asked me to turn it on at all.
Also, keep in mind that no matter how carefully you pack your electronics in your checked luggage, they will NOT be that careful when they pop your bag after it's been checked in. I had an XBOX360 that I'd carefully bagged and cushioned while traveling to Afghanistan, where it's extremely dusty/dirty. When I arrived in Belgium en route, I opened my bag to do some gaming in the hotel and the plastic bag had been ripped open and placed on top of the XBOX. Now, the plastic bag hadn't been taped or sealed in any way so it could simple have been slipped off (and slipped back when the inspection done).
When I complained to a friend who works TSA at LAX she replied, "I don't get paid enough to repackage what I pull apart." So.... I'd say if it's important to you, electronic, and you want it protected, carry it on and as mentioned, have it handy to pull out during screening.