Here is example:

Gigabyte GA-MA790X-DS4 AMD 790X ATX-mainboard AMD AM2/AM2+. 99.90

AMD Phenom II X3 720 Black Edition, boxed. 154.90

Asus EAH4870/HTDI/512M Radeon HD4870 512MB PCI-Express x16. 199.90

A-DATA 4GB Kit (2x2GB) 800MHz DDR2 CL5 50.90

or if u need to buy new PSU also:

Gigabyte GA-MA790X-DS4 AMD 790X ATX-mainboard AMD AM2/AM2+. 99.90

AMD Phenom II X3 720 Black Edition, boxed. 154.90

Asus EAH4850/HTDI/512M ASUS HD4850 PCI Express x16. 151.90

A-DATA 4GB Kit (2x2GB) 800MHz DDR2 CL5 50.90

Antec EA 430-EC Earth Watts 430W. 60.90

These for example.