But dont the Quadro 4s have a different set of hardware for like advanced rendering instructions? Wouldnt this mod just make your system crash frequently?

No it wont cos thats the same mod Nvidia DO :D

This would make you be able to use nvidias 64bit drivers right? if u got the OS for it.

When you modify a chip's ID, you are simply getting more features with Nvidia. Actually, the hardware is capable of doing everything an official quadro can because they use the exact same chip. It's the drivers which use more of the chip when the chip ID is changed. The drivers see the higher ID meaning you payed more (supposedly) and thus deserve more features. I disagree though. If I buy the actual chip on my card, then I feel that it gives me the right to use every bit of silicon on it, otherwise, they shouldn't have sold me that silicon/logic.

And dont forget you'll need a couple of grands worth of intel cpu to boot