If you are sizing for future expansion, you are using too small of a case. 1000 watters go in Antec 1200's and HAF 932's. No way a PSU of that size belongs in a teeny case like that. In order to use all that wattage, you need room to put stuff and you simply don't have it in the Three Hundred....and if it does fit, you'll have trouble keeping it cool.
Your putting in a 5770, even Xfired ATI recommends on;y a 600 watter.
At $230, for that combo, for an extra $14 you could walk away w/ this:
http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.359987
An outstanding case and a simply jonnyguru performance rating of 10 on the PSU.
Here's an alternate at 650 watts $180
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129064
and 750 watts $180
http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.359961
The Silent pro's are very well rated .... but a 700 watter, or better even smaller, is more appropriate for your build
http://www.silentpcreview.com/article936-page7.html