Quote Originally Posted by 4x5
the color isn't gonna make that big of a difference,
Wrong! Cool White (4200K-5000K) is the most useless spectrum on the market, and will not let your plants grow well.

There are 3 spectra to use in CFLs:

Daylight / 5500K-6500K / blue end (best for veg)
Stark White (rare) / 5200K / blue end (best for veg)
Warm White / 2700K / red end (best for budding, good for veg)

Think of light spectra as boobs. 5200K-7000K is the left boob, and 2200K-3000K is the right boob. 3100K - 5100K is the valley between the boobs where not much goes on.