I'm thinking of buying my parents a new computer since they have an old P4 Dell desktop which is rather slow and consumes a bit of power. I'm looking to build the cheapest and most power efficient computer possible. All they do is use Internet Explorer, Quickbooks and Microsof Word. I suppose the only requirement would be able to watch youtube videos in HD with minimal stuttering and support for Windows 7. This is tough for me since I am knowledgeable about high performance computer hardware but not about low power budget systems. Anyway, if you have any ideas please let me know.
Agree with shortstuff, but I'll explain my choice.
I choose the 64-bit version because it's a good choice for the future. However, to keep costs down, I used only 2 GB of RAM. RAM is cheap(ish) and very easy to install, so it would be a very easy upgrade to stick in another 2x1 GB kit. If you'd rather build the PC and leave it alone, definitely go with 4 GB of RAM.
That said, if the budget can reach $500 and committed to being energy efficient, I'd actually go with these Eco sticks. They're low voltage sticks that will lower the power consumption of the PC. With them, the total cost would be $488.
I'm not so sure about that Eco RAM. With shipping it's $19 more than the Patriot RAM. The Patriot RAM runs at 1.5v. It would take you a long time to make up the price difference by the minimal power savings of the Eco RAM. In fact, I'm not sure a lot of motherboards are even capable of under-volting the RAM to 1.35v.