If I create three instances of FSX FOLDERS in drive F.By using:1. 32bit XP 2. 64bit XP 3. 64bit WINDOWS7.................Three different drives booting separately of course.The reason is two-fold, COMPARISON and BACKUP.Delete each of the newly created FSX folders in F. Then use an OLD FSX folder which I have been using for a long while. The folder is titled FSX.I have done something like that in the past and it has worked ok.........barring some addons.....mostly it has worked.I do realize that each of the systems would have its own parameters with different locations of configurations, flightplans and other necessary files which are created in the main system drive. Which would be 'C' (a different 'C' each).My question is this. Are there any changes made within the 'F' location of FSX? Changes that might be FATAL?Please let me know if you have any questions about this madness.Thanks.Abe

Hi Abe,It can work. Obviously, you will need to make a seperate install of FSX on each of your OSs (only 1 install per OS). For the sake of keeping things easily manageable for you, I would use some folder name similar to this for each OS:- F:/FSX_XP32 (for the installation under XP 32-bit)- F:/FSX_XP64 (for the installation under XP 64-bit)- F:/FSX_W7 (for the installation under Windows 7)This way, when browsing you F drive, you'll know to what OS each FSX folder relates to. Since the path to FSX is kept in the registry, each OS will only consider the folder relating to itself.This also mean that you will have to make a separate install of all your addons on each OS. That's a lot of work if you have many. Addons that do not install inside the FSX folder, but at the root level of your F drive will cause problem. Better restrict your addons to aircrafts and scenery.The important thing to avoid is having a single FSX folder shared by all OSs. If you use your old FSX folder, you might be looking for trouble if its content is different from the newly installed ones.Even though, the OS would still be looking for a folder named FSX_XP32, or FSX_XP64 etc. and not "FSX".