Stat tracking software

[Trident]

I currently play on Full Tilt and am considering buying a tracking program like Poker Tracker or Calculatem. Does anybody have any info/advice on any of these programs? I don't think many work for Full Tilt yet, but I'm sure they will come along shortly after the WS. Do they become too much of a crutch? Which help more, odds calculators or opponents' play analyzers? Any help will be appreciated.