This is because under Windows 7, Microsoft has implemented Plug and Play support for SmartCards. You can either simply ignore or dismiss the prompt to install a driver, or alternatively you can disable the SmartCard Plug and Play service by following the instruction below.
To disable SmartCard Plug and Play service on Windows 7.
2. In the console tree under Computer Configuration, click Administrative Templates.
3. In the details pane, double-click Windows Components, and then double-click Smart Card.
4. Right-click Turn on Smart Card Plug and Play service, and then click Edit.
5. Click Disabled, and then click OK.
For enterprise deployments, SmartCard Plug and Play can be disabled by deploying a Group Policy. For information about administrative templates, see (http://go.microsoft.com/fwlink/?LinkId=152390).
Further information about windows 7 and smartcard Plug and Play can be found here: http://technet.microsoft.com/en-us/library/dd979547(WS.10).aspx