Several option:
1) probably the best - select a 3rd party email client such as Firefox or thunderbird as mentioned by Hawkeye 22
2) use microsoft windows live - Yuk
3) Most expensive (unless you have), Use outlook (NOT Outlook express). Comes with the Microsoft Office Suite - Not home version but more expensive version) Had a company supplied copy so that is what I'm using.
4) Most dificault, but doable. Copy over Vista winmail. This is what I did for wife's computer as she hates Change, and liked vista win mail (updated version of outlook express). This requires the use of a computer that has Vista still on it and knowledge of changing the "Privilege" attribute.
Can goole using "vista win mail in windows 7.