VS 2010 Deletion of duplicate Entry from listbox using VB.NET

I want to make a very simple program that remove duplicate domain name from listbox.
So, the URLs will be loaded into listbox.

Must Be In Vb.net

Then It has 2 more button Start and Save button.
Lastly one counter to calculate how many urls in that listbox.

So example..
let say I have a listbox which contains URLs

http://google.com/analytics
http://google.com/insight
http://yahoo.com
http://bing.com/search
http://fiver.com/user
http://fiver.com/categories

Then when I press start button, it will delete the urls that has same domain name. So the output will look like this

http://google.com/insight
http://yahoo.com
http://bing.com/search
http://fiver.com/user

Then I can save the urls from listbox to my disc drive as text file when i write in textbox2.text c:\saved.txt using streamwriter.

Thanks