The conversion the packages use are 1 CFL watt = 4-5 incandescent watts, so a 15 watt CFL is listed as replacing a 60 watt incandescent. From what I've seen a 3x factor would be more accurate for real usage, so a 15 watt CFL only really matches a 45 watt incandescent and you'll need a 20 watt CFL for a 60 watt incandescent.
if you break it, get some thick gloves on, those things have some mercury in there and theres a debate going on that they are in fact quite harmful if broken.