Viewing the series in the original broadcast order is the authentic experience as one would be exposed to the story in the same order that everyone who watched it the first time around had seen it.
Crusade however had many problems during production and some episodes were filmed and/or broadcast before their overall place in the storyline had been finalized. The original broadcast order was changed for reruns to match the best possible continuity. There is also a chronological viewing order as well.
In addition to the many revisions to Crusade, there are multiple preferred viewing orders available online. For any subsequent re-watches of the series please consider J. Michael Straczynski's preferred viewing order.
A google search for "Babylon 5 watching order" will yield lists of the above mentioned viewing orders.
Wikipedia has tons of information about the series and its list of episodes includes all the broadcast dates. There are also many websites dedicated to the series some of which have been in operation since the series was on the air.
The series totals at 5 Babylon 5 seasons, 4 movies including the pilot, another movie that serves as in introduction to Crusade, the Crusade series, another movie that was meant to introduce a series that was not produced, and a direct to video 2-part series.
Babylon 5 is a wonderful Science Fiction property that is beloved by many. Any hope of continuing the series has faded because of the death of some main actors and a lack of interest by current studios. JMS holds the rights to movie production involving the franchise and still shops around the idea of a reboot movie series.