Getting all new grow gear

So I could use some help from the techies on here.

Right now I'm growing with a 400 watt HPS in a 6' ish by 5' ish closet, and I'm just not satisfied with bud density etc...
I'm thinking of selling all my stuff off, but I need some suggestions on what to get. Here are my questions:

1. Can I use a 1,000 watt HPS in that size of a room?
2. Can anyone link to anything reasonably priced on Ebay that they'd recommend?
3 Comments on what I've found below?

http://www.ebay.com/itm/1000w-1000-...558?pt=LH_DefaultDomain_0&hash=item1c364b633e

Thanks in advance

......Bump

You can fit a 1k/1000w light in there if you vent it enough to stay between 75-84f. I suggest starting with the 400 and work your way up, slowly build up equipment for the 1000w. Get a 600w and see how it does. Then get your 1000w. If you think you're ready and can control heat and watering and feed for a 1k light, go for it.