8-16 core Mac Pro with Intel Nehalem-based 32nm processors at 4GHz+, Common Systems Interface instead of FSB, PCIe2.0 with 4 x16 slots and 4 x8 slots, 8800GTX and X2900XTX, and something like those previously rumored Final Cut Extreme co-processing cards, dual Blu-Ray/HVD (i mean holographic versatile disc, not HD-DVD) writers, SATA 6Gbps and SAS HDD connections, 10TB+ internal storage at insane speeds, two 4-port bootable eSATA and SAS controllers, Fibre Channel, dual 10-Gigabit ethernet, HD-SDI capture card with ProRes 4:2:2 hardware encoding, Wireless and wired USB, Firewire 400, 800, and 1600
Oh, and at least 5TB of the internal storage would have to be SSDs.
And it has to be quiet. very very quiet.