I know you already found out how to make the icon on your desktop link to Yahoo and show up as the Yahoo icon. You can also set Yahoo as your default email client if you would like.

Here is the link that tells you how to do it. It does require you to download a small program, but you can specify that you want an icon on your desktop or your Quick Launch bar or in your System Tray that will take you directly to Yahoo email.

I use it on my home computer and only after some initial install issues (I had to install it twice, because for whatever reason the first install did not "stick") it has worked great for the last five or so months.