Your PCIe knowledge lacking? The HardwareSecrets crew's here to help. They know ever-thang thay is ta know about the PCIe bid-ness. Seriously, though, it's a decent primer.

"The main difference among the several types of bus is in the number of bits that can be transmitted at a time, and in the operating frequency used. Nowadays the two fastest types of PC expansion bus are the PCI and the AGP. We listed the transfer rate of those buses in the chart below. The PCI-X bus is an extension of the PCI bus designed to the market of network servers."