insulating basement ceiling

No need to insulated between conditioned spaces.

Spend the money on more aptly insulating the basement walls and air sealing.

Insulation between conditioned spaces is only to help abate noise.

Also do not forget about air sealing around outlet boxes, windows, doors, attic hatches. Those are the largest heat & cooling loss culprits out there. Only time I would insulate the underside of a floor, is if it was over a crawlspace that is non-conditioned.

Treating the basement as unconditioned per code, find your zone here;http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_par002.htm

Insulation for floors- per zone, here; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

Vapor retarder goes toward the warm side- up. If the basement is dry/drafty, you could cover the f.g. with a housewrap on the joist bottoms to stop air infiltration from degrading its R-value, treating it more like a crawl space; http://energy.gov/energysaver/articles/where-insulate-home
Keep in mind you may create problems with the plumbing/ducting uninsulated and colder without the heat loss from above warming them as it does now...

Gary