There are many, many possible mail clients for download and use in the Windows OS. I use Outlook 2010 for all of my email accounts, but since Outlook is a part of the Microsoft Office suite, it costs some money. However, Microsoft produces an alternative in its free Essentials package. You can download the program from here: http://windows.microsoft.com/en-US/windows-live/essentials-home
It encompasses a few programs such as a Photo Gallery, but Windows mail client is in there.