128 bit or 40 bit?

Being outside North America, I have an "export" version of Internet Explorer/Netscape Navigator. These offer 40 bit encryption. (40 bit RC4, I understand). My financial institution has a 128 bit Verisign certificate. To my surprise, they claim this offers 128 bit encryption to /me/. [in transactions to https://secure.mybank.com.xx] I thought my 40 bit client limited the security to 40 bits. Who is right? Please explain. TIA