Hi Quanyum,
Which version do you try to install, SQL Server Express 2008 or 2005?
For SQL Server 2005, supported operating systems are Windows 2000 Service Pack 4, Windows Server 2003 Service Pack 1, Windows XP Service Pack 2.
What’s more, you need to check if you have installed windows powershell properly.
Here are links you could download windows powershell:
Windows PowerShell 1.0 Installation Package for Windows Vista (KB928439):
For x86:
http://www.microsoft.com/download/en/details.aspx?id=23200
Windows PowerShell 1.0 Installation Package for Windows Vista x64 Edition (KB928439):
For x64:
http://www.microsoft.com/download/en/details.aspx?id=11594
If you have any problem, please feel free to let me know.
Hope this helps,
Maggie
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