Apple Mail

I have a problem with Apple Mail and I need someone to help me. I use Snow Leopard and want to use Apple Mail instead of Entourage. But, everyone uses windows around me and when I send email to them, they get my email as plain text. Here is my question... Even I made changing form plain text to rich text in preferences, my mails go still as plain text. Should I do something with Terminal? How can I fix it? Preferences richt text/plain text switch doesnt work. I'll be very happy if I get help.

Thanks,

 

When I send an email from entourage, they get rich text and fonts how I set. This problem occurs only when I send an email from Apple Mail..