Hi Susan, Welcome to Tom's Hardware!
Is Win-7 working fine? A new installation?
Well, there is no default e-mail program in Win-7 like Outlook Express in XP. So you need to install (Outlook etc.) or download (Windows Live Mail or Hotmail, etc.) your choice, to have an E-mail client. Once installed, if you have just 1 email client, it will be you default, or you can set it as your default within the E-mail applet, or in the Control Panel, Default Programs listing.