XP64 on a q9650 clocked @3.88 4G 1800 8-8-8-24-1t GTX 280 clocked. 30fps with most sliders maxed, no light bloom or building shadows and water a 2Low. ASA, GEX, FEX, REX, UTX, Xgraphics FSGenesis mesh and landclass. Tried W764RC - no appreciable difference in anything related to FSX. Unless the RTM is significantly different from the RC (it's been done before) it will remain on my test system and not my flight system.There are some threads with test results on some of the other forums - I *think* Simviation. Still comes down to the fact that there's nothing in W7 that *could* make a difference in FSX other than the 64bit vs 32bit memory handling.And , no disrespect intended, but if you think that you got better performance from XP32 with the /3g switch you did NOT have xp64 set up properly. At best it would be almost the same. I'm not saying that you didn't get better performance just that you didn't get the best out of XP64 or Vista64. the fact that you seem to be getting good stuff from W7 just indicates that you possibly have it set up better. Hope that makes sense.BUT as I always say - it's how YOU percieve the sim - if it works for you and you're satisfied - don't let anyone talk you out of it. Just fly and enjoy.But I would still caution about stating that the "optimum" OS for FSX is W7 - could get some newbies confused.Vic

Very true........perhaps it should be "Best system so far for me" hehe. I did run XO64 for a while, comparing etc... but never really saw much performance difference between that and 32. I spent a lot of time (too much) setting that up...reading forums, sites etc.. The reason why I went back to 32 was mainly because of my music software was having problems with 64. Mind you though I dont think sp3 did any favours for XP. I tried Vista for a few weeks and could not stand it. Seemed like going back to ME for me......lol.

Very true........perhaps it should be "Best system so far for me" hehe. I did run XO64 for a while, comparing etc... but never really saw much performance difference between that and 32. I spent a lot of time (too much) setting that up...reading forums, sites etc.. The reason why I went back to 32 was mainly because of my music software was having problems with 64. Mind you though I dont think sp3 did any favours for XP. I tried Vista for a few weeks and could not stand it. Seemed like going back to ME for me......lol.

LOL. ME, now *there's* an 'optimum' OS for you. Optimum for the stone age! :) But then I'm old enough to remember CP/M and MP/M and a few other early OS's.Even after turning off all the "dumb user" features, there are still things about Vista that make it difficult to work with. Namely the way it handles shortcuts - just too difficult to navigate quickly.After building and working with computers for over 30 years I still find it amazing that the first thing I have to do with a new system is remove all the crap to get it into a state where it's useful.Oh well - think I'll go fly the P-51 for a tad - wish I could still fly one IRL. Hey - anyone got Tom Cruise's number? :)Vic