Strange mixed accounts here!? Running Win98 850HzPIII 512Meg Ram P5 seems to have less issues than P4 on my machine. P4 freezes my system for a long time when exiting (especially if I render anything). P5 does not (even after dozens of renders). My P4 will simply stop working after a couple hours of working on a scene (again, especially if I test render any) P5 has gone all day and into the night - however too many entries into the material room did lock it up, before SR3. I guess there both different on each machine, considering all the other variables of Windoze I guess.. Perssonally I like P5 better but still keep P4 on board cuz it's more familiar. But my P5 loads up much faster and gives less hangs (and so far No crashes except when trying a HEAVY render - high count hair, many lights, etc. See my gallery, even P4 has to do most of my stuff in 3 or more segments to reassemble in Photoshop)