did you try this:
Download Mode Drivers:
*Do not connect the phone to the system until the directions direct.
Install this program, Samsung PC Studio 3, linked below.
After install, the program will open. Make sure under Settings it is set to Not Auto Load at startup.
For safe measure, you can restart Windows. Turn the phone off. Turn phone on by holding volume down + camera + power on and it will load into Download mode. Connect it to the computer. Windows should automatically recognize the device and start loading the drivers (which were installed previously by Samsung PC Studio).
Note: Samsung PC Studio must be closed and not running in the background, Task Manager can be used end its process.
Found here:
http://www.soft-go.com/view/Samsung-PC-Studio_1153.html