Definately need a crank puller. Your BB is a cup and cone style and, as you plan to replace it with a cartridge, you can most likely remove it with a pair of channel locks and a large creascent wrench. Once the crank arms are off, loosen and remove the lock ring on the adjustable cup; remove the adjustable cup; remove the spindle and bearings; and remove the fixed cup. The fixed cup will be the only thing that may give you problems as they can be a bit tough to break loose. Another good method is to clamp the fixed cup in a vise and turn the frame to get it loose. Once the old one is out, clean the threads, grease them up and install the new BB.

EDIT: You will need the correct tool to install the new BB. Get the one that fits the BB you decide to go with. Probably a Park BBT-22 or equivelent.