I am hearing alot of complaining about upgrade limitations and overpricing on the mac pros but in retrospect the 1,1 was a great purchase in 2006. 5 years later the thing is still fast and runs pretty much everything the new models do. In addition, contrary to popular opinion, Apple has been including the 06 in GPU upgrades as it can run the 4870 out of the box.
The question alot of 06 owners have been facing has been whether to upgrade their chips and ram or buy a new system. Its been a tough call every year since the 06 still does everything fine so I have been in a holding pattern..not wanting to spend money on upgrading to octo chips since I may be getting a new pro but still not really needing the new mac pro.