I know this is an older topic, but i'm curious as well.

http://www.startech.com/Cards-Adapters/Slot-Extension/PCI-to-PCI-Express-Adapter-Card~PCI1PEX1

Was looking at those. The price sucks but for some it's much cheaper than buying a new mobo/proc/ram (in my case I could really use 1 for my rig).

If anyone has recent exp. with these please let us know!