Firstly I'd like to post some things about the PCI express architecture.
PCI Express, (also known as Third Generation I/O, 3GIO, and Arapahoe) should allow us to have more than adequate bandwidth for another decade. Unlike its older cousin, PCI-Express is a fully serial interface, rather than the parallel bus architecture found in the current PCI bus. It can be used for many functions, including universal connectivity for use as a chip-to-chip interconnect, I/O interconnect for adapter cards, an I/O attach point to other interconnects. PCI Express can provide I/O attach points for high-performance graphics, 1394b, USB 2.0, InfiniBand Architecture, Gigabit networking and many other bandwidth hungry architectures.
Having all these in mind, it seems that the PCI Express architecture will boost performance, offering next level functions and more bandwidth. Now, about purchasing a PCI-Express based motherboard may not be a good idea since the price is still high.
Maybe in some time when prices fall we'll be able to talk more openly about PCI-express based boards.