With antiquated components flooding the surplus-parts market and free operating systems only a click away, building a fully functional computer has never been such a bargain. No, the $72 PC won’t replace your new dual-core, Vista-shredding laptop. But with its compact size and solid-state components (no hard drive or CD drive), it’s perfect for building into custom enclosures and for specific tasks like Web surfing or playing games. The computer boots from a USB flash drive running an operating system called Damn Small Linux that can handle just about any job.

What do you think happens when you connect your computer to the Internet?

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Meet the ultra-mobile PC, a.k.a. UMPC: a seven-inch screen, Windows XP Tablet PC operating system, plus Wi-Fi and Bluetooth, all in a book-size package that weighs less than two pounds. It’s the vision of the Origami Project team at Microsoft, which recently unveiled design concepts and software for the devices. All Origami-certified UMPCs will feature the Touch Pack, a
finger-friendly add-on to Windows XP with shortcut keys, large program icons and a split