You can use any Internet applications that are capable of running on your computer.
This means that you don't have to use a specific kind of web browser or email program. This is typical of any account at an ISP; all we do is provide you with a connection to the Internet. What you use to surf it is entirely up to you!
If you're looking for a different browser, email client, chat client, etc, we recommend you check out Tucows at http://www.tucows.com