Dual Boot - Can't load XP from 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