There is a semi-secret frill to owning either of Vista's least loved versions. If you have purchased a computer which came with an OEM (bundled with the computer rather than retail) version of either Vista Business or Vista Ultimate, you can legally move to Windows XP Professional without needing to attain an XP license key (though you will need a valid key to get the XP installation going, apparently).

Essentially, you install Windows XP Professional OEM version on your computer, using any valid OEM XP Pro disk and license key, then instead of activating XP over the internet, use the 'call Microsoft' option in the activation window.

Provide the automated assistant with your Windows Vista license key and wait politely while it gets confused and puts you on the line with a real human being (or licensed Microsoft simulacrum of same) and explain that you are invoking your downgrade rights as detailed here. They will provide you with an activation key for Windows XP Professional. This privilege may not last much longer, so get on it while you can!

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- Downgrading Windows Vista Back to Windows XP - 99 Windows Vista Performance Tips and Tweaks - Windows Vista Crash Recovery and Repair Installs - Making Old Software Compatible with Windows Vista - Installing Windows Vista - Safe Mode in Windows Vista For Crash Recovery - Stopping Vista From Thrashing Hard Disks to Death - 10 Steps to a Secure PC - 101 Tips and Tweaks for Windows XP - 104 Killer Tech Tips for Windows XP - 99 Performance Tips for Windows XP - Annual PC Checkup Checklist - Assembling Your Own PC - Back up and Restore Data in WinXP - Browser Hijacking and How to Stop it - Building a Home Theatre PC / HTPC - Burning CDs and DVDs - Cloning WindowsXP - Converting Videotape Into Video Files - Crash Recovery: The Blue Screen of Death - Creating a Weblog / Blog - Creating MP3 Music Files - Decrypting Lost Document & Zipped File Passwords - Diagnosing Bad Hard Drives - Diagnosing Bad Memory - Dual OS Installation of WindowsXP 32-bit/64-bit - Encryption and Online Privacy - Ergonomics & Computers - Flashing a Video Card BIOS - Flash Memory Data Recovery and Protection - Firewalls and Internet Security - Firewall Setup and Configuration - Forgotten Passwords & Recovery Methods - Formatting and Partitioning a Hard Drive - Fundamentals of Upgrading a PC - Hard Drive Data Recovery - Home Networking and File Sharing - How to Install An Intel Socket 775 CPU and Heatsink - How to Fix Homesite Design Mode to Work in WindowsXP/ Vista - How To Make a Budget Desktop Computer on the Cheap - How to Update a Motherboard BIOS - Installing RAID on Desktop PCs - Installing WindowsXP

- Internet Connection Sharing - Legally Copying Software and Music - Linux Part 1: Getting Familiar - Linux Part 2: Installing a PC - Linux Part 3: New Software - Little Known Features of WindowsXP - Making DVD Movies from Video Files - Most Common Ways to Kill a PC - Optical Drives & Recording Formats - Overclocking the CPU, Motherboard & Memory - Overclocking the Videocard - Preventing Data Theft from a Stolen Laptop - Printer Sharing on a Home Network - Quick Guide for Eliminating Spyware and Hijacker Software - RAM, Memory and Upgrading - Registry: Backups, Repairs, and Protection - Remote Access to Computers - RSS Feed Setup & Subscriptions - Setting up an FTP Server in WinXP - Slipstreaming WindowsXP with Service Pack 2 - Spyware Protection and Removal - Stopping Spam - Synchronizing Files and Folders - Unattended Windows 2000/XP Installations - Understanding & Creating Batch Files - Understanding & Tweaking WindowsXP Services - Upgrading A Motherboard Without Reinstalling - Upgrading Win98 to Windows XP - USB Memory Drive Projects & Tips - VPNs and Internet Connection Security - Website Hosting From A Home PC - Website Hosting With Apache - Windows XP Command Prompt - Windows XP Safe Mode Explained - Wireless Home Networking - Wireless Network Security Got an idea for a Guide we haven't already covered? Send it in.