So your wanting CFL's for vegging and an HPS for flowering? You probably know this--but in case you don't--an HPS lamp won't work in a normal light socket. HID (high intensity discharge) lamps (HPS, MH, and CMH) require a ballast in the appropriate wattage for the lamp to run. They're more of a light "system" (lamp + ballast) instead of just a bulb you screw in. Fluorescents use ballasts too but with CFL's the ballast is built into the bulb.
As far as CFLs, in my opinion you want the to find a balance between wattage and number of bulbs. The higher the wattage the more lumens. Higher lumens can penetrate through the canopy better. Lumens don't "add together" across bulbs. So a pair of 3000 lumen bulbs won't penetrate the same as a single 6000 lumen bulb. On the other hand, even higher wattage CFLs don't penetrate very well so you need multiple bulbs spaced around each plant (and quite close to the plant).
When I briefly used CFLs for vegging recently, I used (2) 105w'ers combined with several 27w. My theory was the 105w provided "some" penetrating power while the 27w'ers added coverage. I was going to flower under CFL's also (multiple 55watters and 42watters) but ended up going HID instead. On a side note, I was surprised by the amount of heat generated from my 250 watts of CFL light. In my particular situation, an air-cooled 250w HID has been much friendlier heat-wise.
Higher color temperatures are for vegging and lower color temperatures are for flowering. Color temps are measured in degrees Kelvin, e.g. 2700K, 4100K, 6500K, etc.
Also, ignore the "incandescent equivalent" wattage figures many/most CFL packaging contains. That means nothing for our purposes. The only wattage figure we care about is the actual wattage consumed by the bulb.
Check out HTGSupply.com for some good deals on HID lighting setups. There are many places to buy from though.
Like I mentioned, I started with CFL's. But I ended up deciding that just didn't make sense for me. I now have a 250w HID ballast that will run either a MH or a HPS bulb. I'm much happier all around. I think fluorescents have their place (and I'll still probably use them for early vegging once my space is setup for that). Fluorescents just seem easier to get into when you really don't know what you're doing. But in the end I'm using HID and spent a bunch of money on CFL's that I may never use. Maybe that was just part of the leaning curve I had to go through [shrug]. Whatever you choose, don't forget about ventilation and light cooling. Every situation is different, but I've spend far more money and effort on good ventilation (quiet ventilation--a requirement for me--can be expensive and complex) than I did on my actual light.
$0.02
