Two commonly used scripting languages in the Windows Scripting Host (WSH) environment are Perl and Visual Basic Script (VBScript). On the one hand, you can make a strong argument for using Perl. Perl has mechanisms for handling regular expressions (i.e., patterns or templates that you use to match and manipulate strings without a lot of calls to string-handling functions) that VBScript doesn't begin to approximate. VBScript 4.0 lacks this capability outright; VBScript 5.0, which was in beta testing at press time, supports a regular expressions object, but this object's capabilities are in their infancy. Another advantage to using Perl is that systems administrators have used it to automate administrative tasks for many years, so you can find plenty of stock scripts that you can modify to meet your needs.
On the other hand, VBScript is the lingua franca of the Windows environment. Anyone who has customized a Microsoft Office application has used Visual Basic for Applications (VBA), the superset from which VBScript draws its functionality. In addition, you can easily use ActiveX components to extend VBScript's functionality.