So just to be clear with the X-wing Tie fighter games, you do get CD quality sound/speech from the start? This is not a conversion of the floppy disk versions?
Currently, the Collector's DOS CDs are not included, which are the preferred way to play the game by most people. So there's a lot lacking on the DOS side, because the two games only feature the original DOS floppy releases (well whatever was before the Collector's Editions).
The Windows versions included do feature the speech, but it is lower quality to save space I believe. And the audio is different too, which is now redbook in Windows instead of the better, imuse system in DOS that mixes the music to correspond to what takes place in the game. The redbook audio is not the same compositions as used in the DOS version and people find it to not fit the game as well as the DOS music.
The speech in the windows version, and John Williams redbook audio can be modded somewhat though. The higher quality DOS speech can be inserted and a recording of the music from the DOS version can be used instead of the John Williams tracks, but while it fits the game better, it is not as dynamic as the actual imuse version.
The Windows version does feature "better" graphics, with texture mapping instead of gouraud shading like in the DOS version. Even this some people find to be worse, though that is more a matter of taste, when I tried the Windows version for the first time, I definitely felt the graphics were significantly different and in some ways better and some ways much busier looking which may not be better. The Windows version also has inferior models for a few of the ships from what I read, and the balance / timing of the weapons and levels is a bit different from the DOS version.