get-childitem C:\scripts -recurse | Clear-ItemProperty -Name attributes
Okay. Okay. So this script is actually resetting all of the file properties to Normal. If you absolutely cannot modify the other file attributes then you need a much more granular (and complicated) script which can be found at: http://blogs.technet.com/b/heyscriptingguy/archive/2011/01/26/use-a-powershell-cmdlet-to-work-with-file-attributes.aspx .
MSDN article detailing different file attributes: http://msdn.microsoft.com/en-us/library/system.io.fileattributes.aspx
So why not just use attrib -A [directory]? Because the attrib command tries to write to hidden files (like the page file) and this script does not.