They run a show for two months, if they don't like the numbers, it vanishes.

I really didn't expect Firefly to make it, FOX wants crap they think appeals to the dreaded LCD (lowest common denominator). Originally the X-Files was a decent series, then they began to dumb it down with popular urban legends, I quit watching in the middle of the second season.
There have been quite a few show FOX test ran, some good one's they ran three, four showings then axed them as not instant hits. Some of the best shows around took time to build an appreciative audience
Remember, we're discussing a network that aired the "Moon Landing Hoax" show.

Another good reason to lock my TV into Tech TV, SciFi channel, Discovery, History, The Learning Channel, and Nat Geo Channel

Oops., forgot the most important one Cartoon Network. Grin