i am installing SQL server 2008 express
on a winXP machine + SP3 + PowerShell

but i am getting error
TITLE: SQL Server 2008 R2 Setup
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There are validation errors on this page. Click OK to close this dialog box. Review errors at the bottom of the setup page, then provide valid parameters or click Help for more information.

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BUTTONS:

OK
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and on the last it shows (compressed directory)

what is the problem please