How do I perform a 301 redirect for all old .asp pages? I am trying to figure out a way to redirect all the old .asp pages to a specific page in my Drupal site.

Is there a way I can accomplish this with a web.config file? I cannot use a .htaccess file because the site will still be running on IIS.
Why not use Drupal 7's core URL redirect interface? It has an option for 301 redirects: Configuration > Search and metadata > URL redirects.

I like it because it captures stats on how many redirects are happening.