title: ASP.NET Key/Value List
body: <p>I'm doing a custom 404 page for a large website that's undergoing a redesign.  There are about 40 high-use pages that customers may have bookmarked, and our new site structure will break these bookmarks.  </p>
  
  <p>On my custom 404 page, I want to alert them to the new URL if they attempt to navigate to one of these high-use pages via its old URL.  So I have a couple of dynamic controls on the 404 page, one for a "did-you-want-this?" type of dialog, and another for a "if-so-go-here (and update your bookmark)" type of dialog.  That's the easy part.</p>
  
  <p>To suggest a new URL, I'm looking at the requested URL.  If it has key words in it, I'm going to suggest the new URL based on that, and them I'm firing off the appropriate did-you-want..., and if-so... suggestions on the 404 page as mentioned above.  </p>
  
  <p>So I want to store these 40-ish key/value pairs (<em>keyword/new-URL pairs</em>) in a data structure, and I'm not sure what would be best.  Dictionary?  IDictionary?  What's the difference and which is more appropriate?</p>
  
  <p>Or am I totally on the wrong track?</p>
  
  <p>Thanks for your time.</p>