Dunno whether it's the same version as in this site, but since the one I've downloaded from this site doesn't seems to properly work on Windows 7 (that or perhaps I did a fatal mistake while patching to the latest version).
http://www.ausgamers.com/files/download ... pe-dvd-iso
The version/contents seem to be a bit out of date though; here is the only place to find mods/latest unofficial patches for it (the dvd iso was uploaded in 2007 while the latest update was from 2011-ish).
http://www.openplanesim.com/forums/viewtopic.php?t=4614
The standalone WW1 mod included in the iso may be the old version as well since the mod itself was released on 2009: http://www.moddb.com/mods/fighter-squad ... ld-war-one