I guess your cab ride depends on where you are going in Rome. We usually take a cab- last June it was 67,000 lire (fco-centro storico). My partner is not a big fan of paying more than she thinks she should, but schleping stuff to the train, termini itself and getting either a bus or a cab from termini is worth the extra 20 bucks we pay to go door to door.
Saying that, we had to give the taxi driver
instructions on how to get to our final destination.
I know of one car service -samarkand that is is good and they speak english. If I dredge up the phone number, I'll post it.
lala