MacBook overheats and crashes. Logic board?

What are the symptoms of a faulty logic board? The other night we were going to a friend's for dinner so I threw my MacBook in my case and got in the car. It was about an hour and a half before I opened it up and when I did the thing was just cooking. I've never seen it that hot. Anyway, it wouldn't turn on until I reset the PRAM. And when I did, it only had 35 min. of battery left. It was fully charged when I left. I've been trying to use it very lightly since then. Yesterday the processor got up to 175 degrees just doing normal stuff. I haven't had it over 190 doing video editing for a full hour. Then a couple days ago (the day after we went to dinner), It just went to sleep and turned back on about 5 times in 30 seconds. It did it again last night. I'm a little worried as you might imagine. I bought a backup drive and it will be here some time this week. Any ideas? Could it be bad RAM?

A little background I forgot to include. 2.2 Ghz MacBook w/4gb RAM. I just went through the whole on-off ordeal again just now. I'm running with the 1gb factory RAM right now to test it. I've run all the system maintenance scripts I can find and cleared all the caches and it's still acting up. RAM or logic board?

And if it were spontaneously going to sleep without waking up on its own would that still be the logic board?

I ran all sorts of test on my Crucial RAM but it said it was good. I reseated it anyway. Everything was dandy for a couple days but it just did it again. On, off, on, off, on, off... Only a hard reboot fixes it. Would bad RAM be capable of doing this?

I got a really good battery. I'm going on 150 cycles and it's still at 100% health. I think it was the RAM. I've been running 1gb of factory RAM for the last few days and it hasn't done anything out of the ordinary. After another week I'll know whether to call Apple or Crucial.

Just to report on the status of my MacBook. I've been running with my factory RAM for a few days now without a hitch. Until today. After running at about 135 degrees for an hour and a half, the computer randomly started turning itself on and off. I hope this helps anyone with similar problems.