What kind of an e-mail account are you trying to check from work?
If you have the ability to install programs on your computer you should be able to use any of the popular mail clients on Vista.
The mail program that goes with FireFox mentioned by your friend is Mozilla Thunderbird
Is there a specific problem that you are trying to work around?
Also, I don't know if this applies to you, but be careful about reading your e-mail from work. Some companies will monitor the programs that you install, what you are viewing, and in some cases even log your keystrokes in the name of company security. Be sure you are not breaking a policy that your company will enforce, and that you are not reading email from work if you don't want the possibility to exist that someone else may be "watching" you and the mails you read.