Heat is not a big issue with my m5500. When doing the basic stuff, the case becomes a bit warm (like all laptops) but it is not a problem at all.
After a couple of hours of gaming, the case becomes warmer, but still really acceptable. The GPU stabilizes at 70°C and the CPU at 60 or so. There is quite some hot air going out of the right exhaust, this is where you will find the most heat. If you keep your hand and mouse a couple of centimeters away, you will hardly feel it though.
I just come back from a 3-day LAN party with a bunch of friends (playing COD2, SWAT4, CS:S, AoE3, etc.), I was eager to see how the m5500 would behave, especially heat-wise! I must admit that it went just perfect, it really can handle the load!!
As for Doom3 and FEAR, I have tested both on the m5500 and agree with what has been said so far. Doom3 runs OK maxed-out, FEAR not, but you can easily find a good compromise between visual aspect and framerate.