Wait!!! You have an entire room available and you are growing in part of a closet??? [cooky]
Sweet deal on the new light! What's next? Melissa buy's a 25 site DWC setup??? LOL! Let me look into your future..... I see the 400 being a veg light and a upgrade for flower.... Yes, your future is looking bright!!!
When I started out I had a 2 bulb flouro unit in a 3x3 area hidden in the loft of my garage. Now I am in a 8x12 room divided in two (the entire loft) with soon to be two 600 ballast's and four 4 foot florescent (veg), 6 fans, Desktop PC, sink with running water BLA BLA BLA....... My wife was trying to talk me into a 1000 watt this time around but two 600's will cover better.