TechSpot has put together a budget PC guide, that ends in 2 final configurations.  They are both complete systems, up to and including the OS, the bottom rung is about $600 and the recommended is ~ $1000.  Keep in mind, these will not satisfy gamers, but are perfect for a relative or aquaintence that finds their “web surfing email machine-thingy” slow, and wants a new one. 
“Build your budget box right. Creating a cost-effective PC is more than just assembling from the cheapest parts you can find. It is an important balance of quality, features and cost. For this reason, you will quickly discover that getting the most for your money becomes a major headache. Fortunately, this guide serves as a cheat sheet for choosing the most appropriate equipment and a reference for real-world street prices.

The goals for this article were based on four major criteria: budget-friendliness, adequate performance, upgradeability and useful features. The intended use for such a system is primarily office work, web surfing, common multimedia and modest creative content creation.”

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