Folder names (or similar) without using the / at the end....

I see several sites that using folders like

domain-name.com/folder_name

now I can do the same except that when I host the above and enter it in my address bar it comes up with:

domain-name.com/folder_name/

now what I want is it to stay:

domain-name.com/folder_name

As this looks a lot cleaner is search engine listings and looks nicer in the address bar.

How do you do this?

Here is an example of a page that does the folder but the folder doesn't force a / at the end:

http://www.travel-library.com/canada-saskatchewan


My server information if it will help, I run a windows server, no php support but asp support and my programming knowledge is none.

This is probably a very easy thing to do but I've just never know the trick.

Thanks for the help,
Stephen