you want a MINIMUM of 4 'daylight' CFLs 20watt with a color rating of 6500k plus 2 warm white CFLs 20watt with a 2700k Rating for Veg... that would be fine for vegging 2 plants as they will share the bulbs output.
For flowering you want to Swap the 4 Daylight CFLs for 4 warm white 25w 2700k and use 2 daylight 20w CFLs to balance the light to a more 'natural' light spectrum
BUT.....
as i said this would be a minimum requirement for decent-ish yield etc.
Basically, the more daylight bulbs you can get in during veg the better your plant will grow, and potentially yield..
The more 2700k warm white bulbs you can use during flowering will help make the buds bigger,more compact and resinous..
CFLS (incase you are unaware) are Those energy saving bulbs you see at wally world etc.. plug into a regular lamp holder...use very little electricity... dont get too warm,so thats another hassle you dont have to worry about...
Downsides...CFLs whilst great for vegging, do leave a bit to be desire when flowering with them...but as i said, the more you can get in your grow room, the better the final results.
If poss,and your budget allows... try to get bulbs that are 42watts, they should work more than fine.