600watts gives you some breathing room if you want to upgrade later to an even faster card. Corsair makes great PSUs too. It's a good choice.
Under $200 I'd look at the HD6870 $159 after rebate
http://www.newegg.com/Product/Produc...82E16814102948
or the GTX 560 $159 after rebate
http://www.newegg.com/Product/Produc...82E16814162084
In the $200-$300 price range you have these which add higher performance
HD 6950 $245 after rebate (comes with free copy of Dirt 3 and the dual BIOS switch unlocks the card's shader count to match an HD6970)
http://www.newegg.com/Product/Produc...82E16814102945
GTX 560 Ti $199 after rebate
http://www.newegg.com/Product/Produc...82E16814162074
The best deals are in the $200-300 range IMO. The GTX 560 ti is a very stout card for $200, and unlocking the HD6950 to 6970 level shaders and a little overclock and you have $300-$400 level performance for significantly less. If you are not comfortable overclocking they will both serve you well depending on the games you play (you did mention Starcraft 2 which isn't super GPU intensive) and the resolution of your monitor.
edit: Looking at your link it seems the motherboard DOES use a standard ATX power configuration which is good news for you. You can buy any ATX PSu and it will work so the Corsair you linked from Newegg would work just fine. Any of the cards I linked for you would be significantly faster than what comes stock. Also, you don't have to buy from Newegg, I just use that as a reference. Amazon sells the same components and sometimes at a lower price (amazon offers free super saver shipping on many items as well to save some cash up front). There are cheaper cards you can get as well, look at the HD6850 and GTX460 for example. Personally I'd spend a little more than what the HD6850 or GTX460 would cost and get a little bit more longevity out of it.