difference between XP 64bit and Vista 64bit?

evening everyone,my question seems a stupid one.I know the difference between XP and Vista and I know that using a 64bit OS reduces (or elliminates) the OOM's.So, for now I have made the transition between XP pro 32b to Vista 64bit. Fs-9 works fine except for the aircraft of Wilco.Both the airbus series and the E-jets make that, when I close a flight, FS-9 crashes.Now, I was wondering if this is caused by the fact that I use a 64bit OS (be it XP or Vista) or that it in fact is caused by the differencebetween the 'old' technology of Windows XP and the 'newer' technology of Windows Vista. With other words, Will the crashes go away if I change back to XP pro (64bit)while using Vista for FsX?I am asking this because I can lay my hand on a new, but cheap box of windows XP pro 64bit and I am wondering if it is worth the trouble.Harddisk space is cheap here at my home so I can easily create a complete HD with the OS on it.All tips or ideas welcomeLuc BrusselmansBelgium