There are a lot of older threads on the Mac Pro. Based on the Woodcrest pricing, found at
http://www.theinquirer.net/?article=29510 it seems likely that Apple can afford to put together a quad 2.0/2.33/2.66 set-up at the current prices. My only question is if 1 GB RAM will be standard in the low-end Mac Pro. I'm guessing on a 7800 as the video card, and upgrade to a 7900.
Here's how it could break down on the low-end:
$660 for 2 2.0 GHz Woodcrests + $300 for a video card + $100 for a 250 GB HDD + $150 for the RAM + $200 for the motherboard + $100 for the case + $50 for BT/wireless
That comes to $1560, for a $2000 computer. Seems reasonable.