Its very hard to make a meaningful comment without a few more details about the choices you have made and without knowing pricing options .
I would think in the US you could have a system based on the X2 550 like this
AMD Phenom II X2 550 Black Edition + ASUS M4A78-E AM2+/AM3 AMD 790GX HDMI ATX AMD Motherboard combo $204 [ after mir ]http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.211696
G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 $50http://www.newegg.com/Product/Product.aspx?Item=N82E16820231166
Western Digital Caviar SE WD5000AAJS 500GB $58http://www.newegg.com/Product/Product.aspx?Item=N82E16822136178
Antec Three Hundred Black + Antec earthwatts EA430 430W COMBO $95
SAPPHIRE 100265HDMI Radeon HD 4830 512MB $90http://www.newegg.com/Product/Product.aspx?Item=N82E16814102822
Total is $497