Dear Friends!
Unfortunately this product is not Vista/Windows 7 complatible, but there could be a solution! FS9 crashes confirmed, try to use FSUIPC 3.85. I'm using this version and I have less crashes since then. If you have a crash during load or startup, simply restart game, second time a crash is a rare issue. - (foresight) Think forward create and save your flights and just click flight selector, that way you may observe nothing. Yes, no crash.  ::)  I'm using REX Overdrive for FS2004 also, there is probably no difference.
So, LOAD YOUR AIRCRAFT with aircraft configuration manager (ACE), sadly you can use it only for passangers weight or cargo weight.
NEVER USE FUEL LOAD IN MAIN MENU!  Once you have a plane prepared to startup, hit alt and than Fuel and Playload. Remember crash happens, but don't be fazed!

HAPPY LANDINGS!