Try going to every store and canvass for the best deal... post what you find here and we'll comment and suggest what's a better option.
Let them (computer shops) fill this up with prices.
Processor : amd x2 250 ----------- Price



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Motherboard : asrock board 880 chipset ----------- Price



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Hard Disk : any 500gb ----------- Price



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Memory : 4gig ddr3 1333 ----------- Price



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Video Card : nvidia gt 240 - ati 4670 or better ----------- Price



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Power Supply : fsp 500watts ----------- Price



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Casing : your choice ----------- Price



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Canvass first. I'd suggest you visit Gaisano Interpace, PC Express, PC Quickbuys for these ones (or whatever you favorite computer store is).