450W would be more than enough with that GPU. I would recommend getting a better GPU for gaming though. You would want to look at a minimum of a GTX 560 or HD 6870 for Skyrim if you want 1080P and max details. (One of those would need 500W)
OCZ Fatal1ty 550W Modular Gaming Power Supply compatible with Intel Sandybridge Core i3 i5 i7 and AMD Phenom $69.99 less $20 rebate.
A $210 case? Get Real!
Come back when you get serious about value for money.
With a low budget you can do some saving on a couple of your choices;
COOLER MASTER HAF 932 Advanced Blue Edition RC-932-KKN3-GP Black Steel ATX Full Tower Computer Case with USB 3.0, Black Interior and Four Blue LED Fans-1x 230mm front fan, 1x 230mm top fan, 1x 230mm side fan, and 1x 140mm rear fan
$169.99 a savaings of $40.
If you are using this computer for gaming you would be better off with a Sandy Bridge cpu and not the new Bulldozer AMD cpu which cannot perform at the same level as the Sandy Bridge or the Sandy bridge-E or the Gulftown for that matter.