2'x7'x8' Grow Closet

I'm making plans to turn my closet into a grow room. 2'wide x 7'long x 8'tall. I'm planning for 12 plants in 3 gallon buckets. I will use mh for vegative and hps for flowering. Would 600 watts be good for this closet? I was looking at this setup.
DIGITAL 600 watt HPS+MH GROW LIGHT 600w w REFLECTOR - eBay (item 180175343435 end time Nov-24-08 09:44:20 PST)

Or would I be able to use a 400watt and supplement with CFLs since I don't have a huge budget?