Se Su,
What country are you in?
I would like to inform everyone that I can confirm that version 1.03 of the ASUS MPX can accept the USB 2.0 in the 66/64 PCI slot with overclocking capability.
After reading about an ASUS A7M266-D version 1.04 that works with the 66/64 PCI slot occupied by the PCI USB 2.0 card that came with the board and the JEN setting was in Jumper Free mode, I decided to open the case of my setup and move the USB 2.0 card to the 66/64 PCI slot.
I set the DSW seitches 1-4 to all OFF and left the JEN switch in the Jumper Free mode
Look at this and a closer look
So, version 1.03 with BIOS 1004 will take the PCI 2.0 in the 66/64 PCI slot and still allow you to overclock. When I first try this, it didn't work. It WILL work if you set the dip switches of the FSB to ALL OFF. The manual did not document this one.