First, you don't save a lot right off the bat if you buy CFS bulbs for four or five times the cost of four incandescent bulbs. Let's be real.
Secondly, unless you turn the lights on and leave them for hours, you're not going to save as much in electricity as the ads would have you believe.
Thirdly, no matter what bulb you use, it costs less to use a lower wattage and it costs even less to not use them at all. Do you really need a night light burning all night in the bathroom? Do you need a light every time you go into the kitchen, even though the refrigerator (where you're headed) has a light of its own?
Think about it.