Mac Pro :: 8800gt / EFI Bios Emulator Corrupt?

I have been beating my head against a wall for weeks trying to boot into Windows. So after weeks of searching for a solution and many attempts of re-installing both Windows and OSX. I am at the mercy of some of the very MAC wise folks here. So I will try and be as brief as I can.

I have a first gen Mac Pro that has worked great since I bought it in 2006. I have bought a Gforce 8800GT 1st gen upgrade video card. Bought it the first day it shipped, like a lot of other people. I followed the the thread that pushed apple for a upgrade for us early adopters. And am glad that apple listened to their customers and made a compatible ROM for the card.

So now to my problem and why I think it maybe a EFI issue. While waiting and reading about the then rumored video card upgrade, I tried to use a PC version of the 8800 GT, same card with a PC ROM. Well If I would of read more first I would of known that it would not work, and was really just taking a chance and thought that somewhere someone would make this work. Boy was I wrong. So after taking out the card and putting back in my 7300 stock card, I can no longer boot into windows. I get a blue screen stop error 0X000000CA (0X0000002, 0X89A0B0C0, 0X00000000, 0X00000000). Didn't turn up much searching for that error. So the symptom I have is as follows: power on holding down the option key, click on my windows disk partition on a separate NTFS formated HD, the computer try's to boot into windows, but after just a quick flash of Windows XP splash screen then straight to the blue screen. Now fast forward a week. apple releases the upgrade, took the PC cad back, ordered the MAC upgrade hopping this would fix the problem, It didn't. So I do a total re-install. I totaly reinstall OSX on a fresh HD, run all updates for 10.5.2. I put in another fresh drive in and run Boot camp to install a fresh copy of XP. The CD installs the startup files to RAM, then enters the setup partition/format screen. I chose new partition select NTFS full option, the HD formats. Now windows loads the install files to the hard drive and reboots. Now I am back to where I started. OSX works perfect XP will not even install new, much less boot into the old partition that is on another HD that I have pulled out right now, I also went back to the 7300, no change. I can hit F8 and get the advanced menu, if I select safe mode it freezes and goes to blue screen. If I move either of the cards to another slot I get the same result but the Mac Pro reboots in an endless cycle after a quick blue flash. In the 16x slot it just freezes on the blue screen.

So after searching for someone with the same problem it seems I cannot find a solution other then what I have read about EFI and that it is basically emulating a BIOS so windows can boot up on the Intel hardware. So am I even thinking in the right area? Have I some how corrupted the EFI firmware? Any suggestions? I bought the Mac Pro to run Pro Tools in windows along with Windows only apps. I use final cut pro in OSX, but I spend most of my time in Windows using the awesome power of the machine. I like OSX but it is not a total OS solution for me, I really like having a hybrid, and VM's and such in OSX will not work with Pro Tools.