Reverting from a clean install of Vista to clean XP install (Not an Upgrade - Easy)

1. Using a DVD/CD or USB thumb drive make sure to backup any files you want to keep from your existing Vista install or move them over to a non-system partition (anything but the C: drive).
2. Reboot your computer with your XP cd in the drive, and wait for the screen to say "Press any key to boot from CD", and press any key. Some Bios may be set to automatically boot from cd while others may not do anything and continue to boot Vista. If this is the case you will need to enter your computers BIOS by pressing "Del" or another primary key during bootup. This will allow you to change the boot sequence of your startup from 1. HD 2. CD ... to 1. CD/DVD 2. Hard drive. This means it will look for a CD/DVD to boot before looking on the hard drive for a boot partition.
3. Follow the on screen prompts to reinstall XP.

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Reverting from an Upgrade to Vista from XP- Back to XP (Difficult)

This describes how to manually restore a previous Windows installation on the computer to replace the current Windows Vista installation. To do this, you must use the command prompt, and you must type specific commands at the command prompt to rename and to move folders between the different versions of Windows.

CAUTION: This is a fairly lengthy procedure, although not very hard. I would only suggest doing this if you do not have your XP CD/DVD anymore. And orignally upgraded to Vista from a pre-installation of XP on the computer you bought.

Step 1: Determine whether there is a Windows.OLD folder and whether there is sufficient free space on the Windows hard disk

1.	Click Start, and then click Computer.
2.	On the View menu, click Details.
3.	In the Free Space column, note how much space is available for Local Disk (C: ) under the Hard Disk Drives area.
4.	In the Hard Disk Drives area, double-click Local Disk (C: ), and then determine whether the Windows.OLD folder exists. Important If the Windows.OLD folder does not exist, you cannot follow the steps in this article to restore the previous Windows installation to this computer.
5.	Right-click the Windows.OLD folder.
6.	Windows Vista will determine the size of the folder after several seconds.

Determine whether the Windows.OLD folder is smaller than the free space that is available for Local Disk (C: ) in step 2.

Note If the Windows.OLD folder is two times as large as the free space that is available for the Local Disk (C: ) entry, you may be unable to restore the previous Windows installation.

Step 2: Start the Windows Recovery Environment

1.	Put the Windows Vista installation disc in the DVD drive, and then restart the computer.
2.	Press a key when you are prompted to restart from the disc.
3.	In the Install Windows window, select a language, a time, a currency, a keyboard input method or other input method, and then click Next.
4.	In the Install Windows window, click Repair your computer.
5.	In the System Recovery Options window, click the version of the Windows Vista operating system that you want to repair, and then click Next.
6.	In the System Recovery Options window, click Command Prompt.

The Command Prompt window opens, and it displays the command prompt. The command prompt is where you will type the commands that are described in the following steps.

Step 3: Rename the Windows Vista folders

Note When you type one or more of the commands at the command prompt in the following steps in this section, and you then press ENTER, you may receive the following message:

If you receive this message, go to the next step in this section, and then type the command in that next step.

Type the following commands at the command prompt:

1.	Type the following command, and then press ENTER: c:
2.	Type the following command, and then press ENTER: ren Windows Windows.Vista
3.	Type the following command, and then press ENTER: ren "Program Files" "Program Files.Vista"
4.	Type the following command, and then press ENTER: ren "Users" "Users.Vista"
5.	Type the following command, and then press ENTER: ren "Documents and Settings" "Documents and Settings.Vista"

Step 4: Copy the contents or move the contents of the Windows.OLD folder

Type the following commands at the command prompt:

1.	Type the following command, and then press ENTER: move /y c:\windows.old\windows c:\
2.	Type the following command, and then press ENTER: move /y "c:\windows.old\program files" c:\

Type one of the following commands at the command prompt, as appropriate for your situation.

When the previous Windows installation was Microsoft Windows Server 2003, Microsoft Windows XP, or Microsoft Windows 2000

•	Type the following command, and then press ENTER: move /y "c:\windows.old\documents and settings" c:\

When the previous Windows installation was a different version of Windows Vista

•	Type the following command, and then press ENTER: move /y c:\windows.old\users c:\

Step 5: Restore the boot sector for the previous Windows installation

Type one of the following commands at the command prompt, as appropriate for your situation.

Note D: represents the DVD drive in the following commands. If the DVD drive on the computer is represented by a different letter, such as E:, use that letter in the command.

•	When the previous Windows installation was Microsoft Windows Server 2003, Microsoft Windows XP, or Microsoft Windows 2000 Type the following command, and then press ENTER: D:\boot\bootsect /nt52 c:
•	When the previous Windows installation was a different version of Windows Vista Type the following command, and then press ENTER: D:\boot\bootsect /nt60 c:

Step 6: Restore the Boot.ini file for the previous Windows installation of Windows XP or of Windows 2000

Note Only follow these steps when the previous installation is Windows XP or Windows 2000.

Type the following commands at the command prompt:

1.	Type the following command, and then press ENTER: c:
2.	Type the following command, and then press ENTER: attrib boot.ini.saved -s -h -r
3.	Type the following command, and then press ENTER: ren"boot.ini.saved""boot.ini"
4.	Type the following command, and then press ENTER: attrib boot.ini +s +h +r

Step 7: Close the Command Prompt window, and then click Restart

1.	Type the following command at the command prompt, and then press ENTER: exit
2.	Click Restart.

The previous Windows installation will start.

If this procedure does not work for you I suggest you call Microsoft or locate an XP CD/DVD to use.

Reference: http://support.microsoft.com/?kbid=933168&SD=tech


AMD64 X2 5200+ 2.60GHz | 3GB DDR 667 | RAID 0 SATA3.0 WD Caviars 320GB total | Foxconn MCP61VM2MA-RS2H Geforce 6100 nforce400 chipset | Vista Ultimate x86

There is at least a suitable workaround for being able to install fresh using an upgrade disc w/ out losing your XP license.

The solution lies within Vista's ability to let you install it as a 30 day trial, from the upgrade DVD. You can simply skip entering your CD key, then re-running the installer after it is finished and entering your key then. Unfortunately, it means installing Vista twice in a row. You don't save time, but it may save you a few angry phone calls or a trip to the store if you end up having to do a complete reinstall. MS has still not commented on why they implemented these new, easily frustrating, install “features”.

So I've never tried this, but theoretically you could not have a previous OS installed, and still pay a lesser price for an upgrade disc and still end up being able to use it.

AMD64 X2 5200+ 2.60GHz | 3GB DDR 667 | RAID 0 SATA3.0 WD Caviars 320GB total | Foxconn MCP61VM2MA-RS2H Geforce 6100 nforce400 chipset | Vista Ultimate x86