Unless you print constantly and consistently...you should use cartridges.
The 2 minutes it takes to refill all the cartridges is better then the 5-10 minutes you will spend messing with the CIS on one of these printers.
CIS is for people who's printers are printing ALL THE TIME. Even then in a lot of cases it would still be better to work with cartridges.
The 7720 is a nice printer. Scanner is useful if your going to scan and dont have one already. Cobra ink is what a large portion of the people on this forum use.