dual boot can t load xp menu ntldr missing

Hi all! About to go for surgery, so I have to be quick.
I have three partitions. The first one is a little 3g remnant of when I used to dual boot xp and 98. The second is XP, the third is space for Vista. (WAS Linux.)
I installed Vista the first time, all was good.
Got a new hard drive. Cloned over. Big difference was SATA (3112 controller on board.)
I know about the driver disk for the controller, and used it, but shame on Asus for giving us one that's 4 years old. I extracted the newer one that windows update had put on my XP machine. MARCH 06.
Vista wouldn't boot. I assume the new bootloader was foreign to the WD transfer tool. So - I reinstalled Vista. Started working, and XP stopped.
Restore the boot sector for XP, add Vista to Boot.ini, XP works, Vista hangs during load. Blank screen.
Current situation. If I FIXMBR and FIXBOOT back to XP, and blank the VIsta Partition using XP, which works fine, then install Vista (new SATA driver), I get a working Vista, but XP refuses to load with the corrupt or missing ntldr error. I can switch between by booting off the respective disk and restoring the boot sector for each one, but the other quits working!
Also - Vista keeps losing my video settings at each reboot, and redetecting my monitor setup. That MAY be due to the DVI flat panel I am demo-ing. I can try the CRT to see if that goes away.
Any ideas??
PD