I just upgraded my computer by buying a motherboard (asus m4a78), cpu (AMD Phenom 2 X3 710) and 4gb of ddr2 ram. That's all I needed because I am reusing my 8800gt video card. Total cost? $250. ALso reused my 250gb HD (there's actually a terrabyte internal HD on amazon for about $70). The AMD CPUs are great for the money.

If you are gonna want it to last for 4+ years I'd probably go for a quad core. AMD makes very affordable triple core processors too.

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1985 CA 300D Turbo , 213K mi