Having a major malfunction. Need help!

[digiegg]

UGh I've been at this all day yesturday and today.
Basically Windows won't boot on the damn thing.

I was getting rid of my old computer and wanted to install a ATA (Not SATA) drive into the Mac Pro. I followed the optical drive instructions and installed it.
BADDDD Choice I made. When I booted, it said NDSKRLL.dll or whatever missing.
It kept on trying to boot off the Slave drive(I set it as Slave). I've tried every jumper and it wouldn't boot.
I took out the harddrive giving up the fact that I can use the ATA as a back up and try to boot windows by itself.
It booted, then it shuts itself down. Asks me to choose if I want to start in safe mode or normal mode then shuts down again. Repeat.
Basically it wouldn't boot. Now I tried reinstalling windows without formatting because I have very important files in windows.
First I get the NTOSKRNL.EXE Missing.
I tried re installing it 3 times and now it has 3 different XP bootups.
All giving me Hal.dll is missing. Yes I went throught the bootcfg /rebuild method and still it gives me major trouble.
Any way of going about this?

Ugh... I'm so stuck right now...