Run the preboot diagnostics if you haven't already done so. See Windows Reinstallation Guide/Running Dell Diagnostics (Page 413):
http://philipyip.wordpress.com/dell-community-forums/
I would second the recommendation to upgrade to Windows 7. Vista is being phased out (Microsoft have no Office 2013 or IE10 support for Vista).
However if you are installing Windows Vista ensure you load the SATA drivers during the Windows Setup and if your Reinstallation DVD doesn't have Service Pack 1 follow the instructions in the guide to slipstream it.
