Hello,This is offered as information from my experience only. While it may be somewhat unique, it is offered in good faith.I have a complex flight simulator setup. I use FS9 and FSX with a rather big GOFLIGHT setup. Recently, I decided to add the PMDG 737NG to myFSX setup. I waited until the dust settled and the SP1 was delivered. I downloaded the item and installed it. It seemed to go OK but I found that it would notACTIVATE. I looked in the DLL file and the entries were there. The dll required for activation just would not run. I sent a Support request to PMDG and theywere very responsive. I tried all of their suggestions used to get an XP installation to work. None were successful.I found a coupon for a FSX upgrade to my IFLY FS9 737. I got the item and found the same problem. It would not activate. At this point I went to thePMDG LIVE Support. They were once again very helpful. After spending a lot of time poking around in my system, they concluded that the problem wasa "deep XP" problem. Their suggestion was to move to Windows 7. I thought about this and decided to spend the money necessary to go to WIN 7.Well, after many hours of installation and setup, the problem was solved. It was in fact the Windows XP that I had on my system. I have a Dell XPS with a quadCPU and 4gigs of RAM. My hardware is very "upscale" and the system was always up-to-date.I hope this experience will help anyone who is considering moving up to these complex sims on a Windows XP system.Cheers,Ron SagelNEAR KCHS

Hello,This is offered as information from my experience only. While it may be somewhat unique, it is offered in good faith.I have a complex flight simulator setup. I use FS9 and FSX with a rather big GOFLIGHT setup. Recently, I decided to add the PMDG 737NG to myFSX setup. I waited until the dust settled and the SP1 was delivered. I downloaded the item and installed it. It seemed to go OK but I found that it would notACTIVATE. I looked in the DLL file and the entries were there. The dll required for activation just would not run. I sent a Support request to PMDG and theywere very responsive. I tried all of their suggestions used to get an XP installation to work. None were successful.I found a coupon for a FSX upgrade to my IFLY FS9 737. I got the item and found the same problem. It would not activate. At this point I went to thePMDG LIVE Support. They were once again very helpful. After spending a lot of time poking around in my system, they concluded that the problem wasa "deep XP" problem. Their suggestion was to move to Windows 7. I thought about this and decided to spend the money necessary to go to WIN 7.Well, after many hours of installation and setup, the problem was solved. It was in fact the Windows XP that I had on my system. I have a Dell XPS with a quadCPU and 4gigs of RAM. My hardware is very "upscale" and the system was always up-to-date.I hope this experience will help anyone who is considering moving up to these complex sims on a Windows XP system.Cheers,Ron SagelNEAR KCHS

3 questions, is your FSX version SP2 or Acceleration?, Are you using the /3GB /USERVA=xxxx options in your boot.ini? What is your video card specs. (GPU, Memory)?

Hello,Service pack 2 installed and checkedboot.ini is as you askedNinvida 9800 GT with 740mMy system, now running FSX and FS9 is humming along on Windows 7. FSX at 39FPS and FS9 at 50 FPS.The PMDG ONLINE SUPPPORT (Live hookup) checked my entire system when it was on Windows XP.We could never get it to work with either the IFLY 737 or the new PMDG 737.I have no clue what the "deep XP" problem really is - I only offer my experience to those who may be in a similar situation.Thanks,Ron Sagel

Hard to say what your 'deep' WinXP problem was, but i'm still running XP with more addons installed in FSX than probably 90% of the users here, including all PMDG planes and never had one issue like that. Glad you got it fixed though.

Same here, although no NG...

Hello,Believe me, I did not like the idea of investing another $200 in my flight sim system. I had installed, like maybe you , a ton of addons over the years. It was alway seamless. Both my FS9 andmy FSX ran great. I also ran XPLANE 9 on the same system with my GOFLIGHT equipment with no installation problems.This was a totally new experience. Only those two (2) installs, the FSX PMDG 737 and the FSX IFLY 737 would not install. They would appear to be installed and the DLL file was contructedcorrectly. However, when the FSX system loaded up, the DLL's indicated that they were loading but they never would execute. Beats me! My end considerations came from the TECH people atPMDG and at IFLY. They were stumped too but had the same conclusion - Go to Windows 7.I'm very pleased right now with my sims - my system is running on three computers with Wide FS and it runs great. The PMDG 737 was worth the $ and the efforts.Cheers to all,Ron SagelNEAR KCHS