After installing the Canopus NX boards I ran out of PCIe slots and I wanted to put an internal express34 reader
Anyone know of an internal reader that uses the PCI-X slot?

A.f.a.i.k. you need PCIe (PCI Express) to connect ExpressCard. There's no 'bridge' to support PCI-X that I'm aware of.

There are PCIe expansion units though that can add the required slots to your system. Like these: http://www.magma.com/products/pciexpress/index.html

George/