no, that's not entirely right stocky
PCIe can be used for anything - it is currently used for video cards, and RAID cards. It will accommodate the phsyx engine card and eventually sound cards...but don't hold your breath. So E isn't just graphics.
PCI-X is basically a souped up faster clocked 64-bit PCI slot at 133Mhz. The next slot down is 64-bit 66Mhz PCI. Then in the SAME family is the PCI 32-bit at 33Mhz.
Animal: you could probably install that card in a 32-bit slot, but what's the point? get a PCIE-8x form factor controller and get SCSI and no bus bottlenecks.
PCI 32-bit to PCI-X are really the same bus technology whereas PCIe is the totally new standard that shares very little with the old stuff in terms of how data is moved.