I wouldn't bother salvaging the 2gb ram and 850 is kinda a low budget... Are you interested in building a custom because it the best bang for your buck and isn't too difficult. If so, I would recommend PCPartPicker, it a website with nearly all componets and prices from various websites. Maybe find a pre made design or craft your own. I wouldn't really recommend this if you don't know much about the inside of a pc but if so, it's your best bet. If your trying to find a prebuilt that meets those requirements then you may need a bigger budget.