Your end CFL's will need to be within a foot of the plants at all times to really make any difference, just keep that in mind(make them moveable). Also I believe the point in having a cool tube is so you can have your light as close to your plants as possible, thus having much better light penetration.

Good luck

edit - oh yeah how much are those CFL's you are planning on using? You would probably be able to save dough if you bought 23w CFL's and some 4 light vanity bars, and a cord to hook it all up. Makes the light more spread out and not focused at one single point. Just a suggestion though, do what feels right to you.