No problem man, you'll be happy with your choice. Is that fan a 6" fan? I was running a 400 and a 600, back to back, with a 6" fan pulling air through them, and my carbon filter systen, and it worked really well. I'm not sure how many CFM it's rated for, it's in the upper 400's, if I'm not mistaken. Should be pretty similar to your fan, and since you are only running a single 1000, it should work just as well, or better than the setup I was running. I currently upgraded to a 1000, but haven't had it up and running yet, so i can't report on it, just yet. Also, I should report that my growroom is alot bigger than your's, so heat isn't as much a problem, for me. My grow area is only about 4' x 4', but the whole room is like 7' x 9', so it takes alot more to heat it up, than an enclosed grow tent. Go with an 8" fan if you want to be extra sure. Overkill is never a bad thing, because you can always dial back, if you have to. If you're underpowered, you don't have that option. You have to run full-steam, and hope things don't get outta control.
Another thing I've found that helps cooling, on setups that have carbon filters inline with their lights, is to run bigger filters, or more filters, than recommended. For example,.....with a 6" fan, run an 8" filter, or dual 6" filters. A single 6" filter will reduce airflow quite a bit, forcing your fan to really 'pull' the air through. Double the filters, and the air will flow much more freely, increasing cooling efficiency. I run dual 4" filters on my 6" fan setup, and when they wear out, I'm going to go bigger, to help keep temps even lower. Better yet, keep your filters on their own seperate fan. That makes for the most effective air-cooling. If I had the option, i'd do that, and have my fan drawing cool air from outside, through my light, then back outside. I just don't have enough inlets and outlets, at the moment.