this might help you
http://support.microsoft.com/ph/11732#tab0
this found on same page under how to install windows vista
Perform a clean installation
There are two ways to perform a clean installation of Windows Vista. The first method is to install Windows Vista by running the Setup program from the current version of Windows on your computer. The second method is to start the computer from the Windows Vista DVD. First, try method 1. If it does not work, try method 2.
Warning In a clean installation, existing data on your computer is deleted. This data includes personal data, settings, hardware driver information, and software programs. After you install the operating system, you must also reinstall all programs. Make sure that you back up personal data to disks or other external storage devices before you perform a clean installation.
Method 1: Perform a clean installation of Windows Vista by running Setup from the current version of Windows
To perform a clean installation of Windows Vista from the current version of Windows on the computer, follow these steps:
1. Start the computer and make sure that the current version of Windows has started.
2. Insert the Windows Vista DVD into the DVD drive and then close the drive tray. Wait a moment for the Setup program to start automatically.
3. If the Setup program does not start automatically, follow these steps:
1. Click Start and then click Run.
2. Type Drive:\setup.exe and then click OK.
Note Drive is the drive letter of the computer’s DVD drive.
4. When the Setup program starts and the Install now screen appears, click Install now.
5. When the Which type of installation do you want? screen appears, click Custom (advanced). The follow the instructions to install Windows Vista.
If Windows Vista is now running on your computer, you have completed the installation successfully.
If the installation does not finish or you receive an error message, and you are comfortable trying to troubleshoot the problem, go to the "Troubleshooting" section for more information about common issues and their resolutions. If you are not comfortable trying to troubleshoot the issue, go to the "Next Steps" section.
Method 2: Perform a clean installation of Windows Vista by starting the computer from the Windows Vista DVD
Note The computer must be configured to start from the DVD drive. For information about how to configure the computer to start from the DVD drive, see the documentation that is included with the computer. Or, contact the computer manufacturer.
To perform a clean installation of Windows Vista by starting the computer from the Windows Vista DVD, follow these steps:
1. Start the computer.
2. Insert the Windows Vista DVD into the DVD drive and then close the drive tray.
3. Restart the computer.
4. When you receive the "Press any key to boot from CD" message, press a key.
5. Follow the instructions to install Windows Vista.
If Windows Vista is now running on your computer, you have completed the installation successfully.
If the installation does not finish or you receive an error message, and you are comfortable trying to troubleshoot the problem, go to the "Troubleshooting" section. If you are not comfortable trying to troubleshoot the issue, go to the “Next Steps” section.
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Troubleshooting
"Upgrade has been disabled" error message When you try to upgrade to Windows Vis...
"Upgrade has been disabled" error message
When you try to upgrade to Windows Vista, the Upgrade option may be unavailable. If this issue occurs, you receive the following message:
Upgrade has been disabled
This issue may occur if one or more of the following conditions are true:
* You cannot upgrade the operating system to Windows Vista. (Not every Windows operating system can be upgraded to Windows Vista.) Go to the "Next Steps" section.
* You did not start the computer by using the current operating system. Instead, you started the computer from the Windows Vista DVD. To resolve this issue, start the computer by using the current operating system. Then, run the Setup program.
* The operating system is installed on a partition that uses the FAT32 file system. To resolve this issue, convert the file system on the partition to use the NTFS file system. For more information about how to resolve this issue, click the following article number to view the article in the Microsoft Knowledge Base:
307881 (http://support.microsoft.com/kb/307881/ ) How to convert a FAT16 volume or a FAT32 volume to an NTFS file system in Windows XP
* The partition on which you want to install the upgrade to Windows Vista has insufficient space on the hard disk. To resolve this issue, free additional space on the hard disk. For more information about how to use the Disk Cleanup tool to free hard disk space, click the following article number to view the article in th