I already have the Babylon 5 Collection, which includes the entire series (as well as the spin-off series Crusade), and the movies (except for the Legend of the Rangers and The Lost Tales). The one thing it doesn't have is the original broadcast version of The Gathering. The version included in the movie collection is the TNT presentation of The Gathering, which is something of a Director's Cut, with certain scenes edited out, certain previously deleted scenes edited back in, etc. Certain portions of dialogue were re-recorded for the TNT presentation as well.
The original broadcast version of The Gathering is included here on Amazon as a bonus episode of Season 1 digitally, and given the price, I could hardly pass it up, seeing as how it makes an interesting contrast to the TNT presentation, not to mention having the opportunity to see it in its original infamy. :)