I only acquired FSX about a month ago. I have lots and lot of FS2004 software and thru the years remember ( I think) that about 40-50 % of the software support both. Whats the easiest way to discovered which of my many FS2004 programs also support FSX? Thanks jerryPS I'll probably say, Why did'nt I think of that ! I say that a lot lately. :(

-check the readme, manual or other documentation-check the developer's site-install it and see if it works

I don't know if you have any PMDG products, but their Beech 1900C/D will work in FSX with some modifications to the flt.sim text. You can copy and past just about everything right from your PMDG folders into FSX in the proper place. I put the guages in the panel folders instead of the guage folder when I swapped it over.