VBScript as the default scripting language for Active Server Pages.
There's a small but measurable performance degradation on pages where the scripting language is set explicitly, so unless you have a reason to change the scripting language for an individual page to something other than the default, you're much better off sticking to the default and omitting the @Language directive.
To change the scripting language in IIS, select a site or virtual directory to change, then choose Properties from the Action menu in the Internet Services Manager. Then, on the Directory tab (Home Directory, if you're configuring an entire site), click the Configuration button. In the resulting dialog box, click the App Options tab and change the default language.