When the new msn search launched it didn't take me long to notice the rss button at the bottom of each search result listing. At first I thought the notion was completely absurd. In all honesty I cannot think of any good reason to subscribe to search results in an rss reader or you mail client. As I investigated a little bit more I noticed that the results were driven by the query string and that I could in fact adjust my results by adjusting the query string. I quickly realized that you could include msn search results in your application or web site by aggregating this data. Like google search msn supports the search word "site:yoursite.com", So by combining these 2 features you can create a search engine for your own site using msn's results.
In the example below I am building the query string on the fly with the searchstring typed in my web form. I then parse the Rss feed with a xsl style sheet and display the results. The pagination is accomplished by passing parameters to the XSL file and handling the pagination within the xsl. To view this example click the link below.
MSN Site Search Example 
As you can see the search works very well and is very fast. You can try searching my site for something like "asp" or "xml" to generate a sufficient amount of search results.
I am making my code available for download please feel free to download it and use it on your site. It will work on any server that will run asp.net. There are only 2 variables that you need to change to personalize the search results to your site. In the aspx file you will find 2 variables "sitename" and "resultcount". Sitename is the fully qualified domain name of your site and resultcount specifies the total number of results to return. You may want to adjust this based on the amount of content you have. The less total results you download on each query the faster it will run.
MSN Site Search Example - Download Source Code (.zip) Google Site Search vs. MSN Site Search In addition to the msn search I have also implemented a
google site search on my web site. The MSN site search is faster and more reliable than the google site search. It is also much easier to setup. The google api requires you to download a wdsl and then compile that on the server. You can then access the search via an object. Though a good exercise it seems a bit more complicated than need be when compared to the elegance of a simple RSS feed.
That being said there are some major advantages to the web service approach. Since msn makes its search results public there is really no way for them to authenticate or track where the results are being used. They really can't tell the difference between someone clicking the button, reading the results in their mail client or using it to search their own site using the script above.
Also though it may be difficult for Microsoft to track where its feed is being used the licensing information within the RSS file specifically states that the results are not to be used for commercial purposes. As I understand to google api is free for all for up to 1,000 searches per day. So if you are building a commercial web site I would recommend using the google search api, but if you are just looking to implement a great quick search on your personal web site the msn site search is a great choice. If you do decide to use this script on your web site please post a link so I can take a look.
note: This article has been updated please see Search Your Site Using Windows Live Search (Part II)