Thunderbird

If you need an email program, I would highly recommend the free, open-source Thunderbird, which is put out by the same people that make Firefox.

It is very customizable and capable of checking multiple accounts, and has the advantage of not being as susceptible to viruses as Microsoft Outlook or Outlook Express.

I use it for my personal email accounts (unfortunately, I have to use Microsoft Outlook at work).

When you install it, it will ask you if you want to import your settings and emails from some other programs, which makes it easy to switch to Thunderbird.

Like Firefox, it also has multiple extensions available to extend the functionality of the program, but there aren't nearly as many. Or you can stick with the default program.

Thunderbird works on Windows, Linux and MacOSX.

Check out the Thunderbird website