If the leads are terminated straight-thru (not bent over) than vacuum desoldering is the way to go. Apply liquid flux to the joint. Tin your iron. Heat joint until solder liquifies and suck it away. You will find there wil be a sweat joint left anywhere the lead actually touched the board. An orangewood stick (The pointed sticks women use for manicures) will easily break these if all the rest of the solder is gone.
Once you are done the chip should simply drop out. If not check all the pins.
To replace, tin all the pads by applying solder and sucking it away. Should leave a smooth shiny surface. Apply liquid flux and solder the new chip in place. when done clean the board with rubbing alcohol.
With practice its not to bad. Mind you I cheat as I have access to a Pace rework station at work :-D .
Things you need:
20-25 Watt solder iron with small chisel tip.
Liquid RMA flux
Small diameter 70/30 (better yet 63/37) tin/lead solder
Solder Sucker
Orangewood sticks
Small needlenose pliers
Rubbing alcohol or aerosol flux remover.
