Your video card is running in PCI mode because the aperature size is set too low. It should be set to either 64 or 128MB. (As correctly noted above.)
As for the AGP speed, you might be able to set the max transfer rate in the bios, and adjust it in Smartgart. There's currently no significant performance benefits to AGP 8x versus 4x, so don't worry about it too much if you can only get the card to run at 4x.