Sorry i really should ahve said more. I believe 'some' 64bit vista systems may have had no problems, but mine and many others have a random crashing issue with ETW, that no one seems to know what the cause is and CA can't be bothered fixing it. Having said that ETW is very stable on my XP 32bit install and I do not have random crashes with ETW on my XP 32bit install. So if you play it its recommended on xp. On 7? I ahve no idea I haven't installed my free copy yet.