If you install Nokia PC Suite (http://www.nokia.com/pcsuite), then you can use the "Phone Browser", which is a Windows Explorer extension, to access files on the phone (phone memory or memory card).
The 3230 does not have, so called, USB mass storage support and without that support you need something like PC Suite to make it visible to the PC.
And you (or any user-level application developer) cannot add the USB mass storage support to an existing device, if it isn't present on the device originally.