I still think that it will work in Software mod of the Crossfire or Sli (if nvidia didn't lock the ULi chipset in their driver... this would be sad since they own Uli since 2006).
AGP+PCI-E
http://www.ocworkbench.com/2007/articles/SLI_using_PCIe_and_AGP_Cards/g1.htm
PCI-Ex16 split in...
Yes it will work!
See this news:
http://xtreview.com/addcomment-id-1755-view-AGP-+-PCI-e-SLI.html
Although the performance won't be as good as with a hardware Sli or Crossfire since the cards won't be linked with a bridge. It will give you a Software Sli or Crossfire