Here's what ive got so far, let me know where you see room for improvement/money saving! Budget max is $600.
AMD Phenom II X2 550 Black Edition Callisto 3.1GHz Socket AM3 80W Dual-Core Processor Model HDZ550WFGIBOX - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103680
GIGABYTE GA-MA770T-UD3P AM3 AMD 770 ATX AMD Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128392
G.SKILL PI Black 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL4D-4GBPI-B - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231209
Western Digital Caviar Black WD6401AALS 640GB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136319
Antec Sonata III 500 Black 0.8mm cold rolled steel ATX Mid Tower Computer Case 500W Power Supply - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129024
LITE-ON SK-1788/BS 2-Tone 104 Normal Keys PS/2 Wired Standard Keyboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16823107120
SAPPHIRE 100259L Radeon HD 4870 512MB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102810
Subtotal: $583.94
Only need parts listed here.
AMD Phenom II X2 550 Black Edition Callisto 3.1GHz Socket AM3 80W Dual-Core Processor Model HDZ550WFGIBOX - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16819103680
GIGABYTE GA-MA770T-UD3P AM3 AMD 770 ATX AMD Motherboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128392
G.SKILL PI Black 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL4D-4GBPI-B - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231209
Western Digital Caviar Black WD6401AALS 640GB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136319
Antec Sonata III 500 Black 0.8mm cold rolled steel ATX Mid Tower Computer Case 500W Power Supply - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129024
LITE-ON SK-1788/BS 2-Tone 104 Normal Keys PS/2 Wired Standard Keyboard - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16823107120
SAPPHIRE 100259L Radeon HD 4870 512MB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Retail
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102810
Subtotal: $583.94
Only need parts listed here.