of you looking for an affordable workstation or even entry level server board with PCI-X slots, the upcoming Asus P5E3 WS Pro might appeal, as it's based on the X38 chipset and offers a pair of PCI-X slots.
It could make an ideal workstation board as it also has two x16 PCI Express slot, a single x1 slot and a standard PCI slot. Other features include eight SATA ports as well as twin eSATA ports, dual Gigabit Ethernet, FireWire and 12 USB 2.0 ports.
PCI-X slots are mainly used for specialized server add-on cards such as RAID controllers, but they're also used for some other high-end products and the standard is something of a predecessor to PCI Express.
The board should be available shortly and it should cost around €255 when it arrives.
You can check out some more pictures of the board here