[reichman]

You can get used HD Native PCIe cards on eBay. But I don't think staying in the cheesegrater ecosystem is a good investment at this point.

Get a refurb trashcan. You'll be stunned by how fast it is, and you'll have money left over to invest in the new Mac Pro that theoretically comes out next year. Even a 4-core trashcan will have enough processing power to be an upgrade over your HD3 system. 6-cores are the sweet spot though.

Yes, you need Ultimate to mix in surround and to use an ICON.

Good luck!