Haha, well in 10 weeks or so you will know why we use 600w lights.
Well with the light you have there now you might be lucky to get an eigth in the end.
Don't give up on the 600. Just read more before acting. Cool it properly and it's fine. My last plant was toching the glass of my 600 with no heat problems, it did end up bleached in one are but still pulled 6 zips out.
The one thing you absolutely need right now is a thermometer with a min/max display. You stat adding cfls and you might get the same problem. Cfls, when you have enough of em per area, get hot too, just in a different way.