The Zion Hauptwerk PC upgrade is complete. Everything went perfectly (once I figured out I had forgot to connect power to the EMU PCI card to power the outboard MIDI/Audio dock).
Operating system is XP-64, EMU-1820 Audio, (2) Planar ELO compatible touch screens.
The toughest thing was finding compatible XP-64 drivers for the Moschip SD-PCI-2S dual serial port adapter.
The ELO drivers for XP/Vista installed and worked without a hitch - using serial cables.
[EDIT] So here is the complete system
Motherboard is
ASUS P5QL-PRO - Chipset Intel P43 - 4 slots-DDR2 Max 16GB
Processor is Intel E6600 - 2.4GHz Core 2 Duo - 65nm
RAM is Kingston KHX8500D2K2 - (2) 2GB DIMMs with heatsinks -
Video is ASUS EAH3450 (ATI Radeon 3450) with 512MB DDR2, passive cooling.
Hard Dirve is Seagate Barracuda 7200.10 - 80GB - Plenty for 2-3 dry Sample Sets
MosChip SD-PCI-2S dual serial port PCI adapter (for touchscreens)
EMU-1820 PCI audio + Behringer ADA8000 (16 channels total)
I have no idea what the Polyphony capability is. It's more than adequate for a 40-50 rank dry organ loaded in mono. We used to use a 3 GHz P4 with no issues.
If I had the budget, the most pressing concerns would be:
To upgrade the audio to 24 channels. If anyone wants to donate $1400 for a MOTU 24/io, please let me know! I'll trade the EMU 1820 with (2) Behringer ADA8000 units straight across!
To replace the SATA hard drive with a 60GB SSD drive.