You should look for "Arctic Silver 5", it is a thermal grease and to my knowledge, doesn't evaporate over time.
I have heard lots of responses to the question "which runs hotter, Intel or AMD?", but the truth is, it depends on the model of your CPU, the quality of cooling, or the ambient room temperature.
Intel have a lower temperature threshold so that would suggest that their CPU's run at a lower temperature, they are hardly going to have operation temperature and maximum temperature too close together, because that is just waiting for disaster.
Intel run cooler but their maximum temperature is lower, AMD run at higher temperatures but their maximum temperature is higher.
[size=0.5]Full Aluminium ThermalTake Case
AMD Athlon XP 3200+ *400 FSB* Barton (2.2GHz)
ThermalTake Volcano 11+ Xaser Edition Air Cooling
1024MB Corsair TwinX XMS 3200 (Dual Channel 2x512) 2-3-2-6
256Mb XFX 7800 GS EXTREME
2x WD Raptors (10krpm 8MB Cache) 36.7GB using RAID -0
Video Logic SonicXplosion 5.1 Soundcard[/size]