===Kegging with Natural Carbonation===
You can naturally carbonate the beer using corn sugar if you like. The recommended amount to use for priming is about 1/2 what you would normally use when bottling -- approximately 1/3 cup for a 5 gallon batch. The only disadvantage of natural carbonation is that it takes some time to reach full carbonation and it can leave additional sediment in the bottom of the keg.
A slightly cleaner and faster approach is to force carbonate your beer using the pressure provided by the CO2 tank. The pressure needed varies with the temperature of the beer and desired style. CO2 dissolves much more easily in cold beer than warm beer. It also dissolves more completely, which is why many of us use a separate refrigerator to carbonate and store the beer. You can use a tool like BeerSmith to calculate the carbonation pressure needed for a given desired CO2 level and temperature.
Kegging is in many ways much simpler than bottling, and after you get over the initial sticker shock you will quickly wonder how you ever got along without a keg. There is something beautiful about coming home and drawing a pint of your favorite homebrew off your own kegging system.