Cool new features in it too, an AEROBATIC mode...cool!
I know on their forum they were discussing something about being able to use helicopters properly this time. I hardly ever find myself flying the whirley birds, but it was something I felt was missing in the FS9 version. Hopefully they were able to implement this in the X version.
Anyway, FSPX is on the top of my list for FSX addons. Hopefully it'll work ok on a vista 64bit system.