DO NOT use the Windows Sound Recorder. Ever. Search for free programs on the internet, buy one, or *ahem* acquire one by alternate means.
As for the format, it's 22050hz, 16-bit, Mono. Some sounds, such as stall horns, buffets, check six calls, warnings, and wind effects (you should see a pattern here) can be in stereo. It's just that the sounds that use the DirectX 3D Sound system have to be in mono, such as Eng files... Though oddly enough, Flaps and Gear don't work in stereo.
The sound system on this game really needs an overhaul, for obvious and not-so-obvious reasons. But mostly for the obvious ones.
