If you are thinking about upgrading from a PCI to an AGP then throw it away, it's time to buy a new computer, you’re not even in the same decade with that mother board.
AGP was obsoleted when PCIE came out 7 years ago
PCI and PCIE are not the same. PCI data rate is 1x AGP is an 8x and PCIE is an 16x
Today the standard is moving to PCIE2 which is just a PCIE with increased voltage.
Eerrrrrr. Standards are moving towards PCIe 3.0.... you're a year behind Toms....