Okay...So,I've got the Xena 3.5 driver loaded, finally Switching the Xena Card to a PCI-X slot was the simple fix. It just didn't like the PCI-"E" slot I stuck it in. Silly wabbit! What was I thinking.
The 64bit driver loaded flawlessly. Machina and Coded are working fine. Playback and capture seem to be working flawlessly. Premiere gives me the option to use the AJA audio card, but not the capture facility. I guess now, I'm like everybody else with a Xena / CS4 system anxiously awaiting the arrival of a CS4 capable driver.
Everything else seems to be smooth as silk with my spankin' new XP64bit/CS4/8 Core Xeon / 16GB / 4TB storage / Xena LHe system. oh yeh, except no CS4 Driver. My birthday's in april maybe, but I'm hopeful AJA will give all of us a beautiful gift of CS4 Integration.