dj,
Your boot.ini looks ok.
Mine is similar, but slightly different:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect
My guess would be that something got messed up on the 80 GB drive that you use to hold important files - probably happened when Vista interacted with the drive. It may be that the drive is having issues, and this is the result.
Have you already tried to insert the XP CD as requested by the message at boot to repair the files? If so, what was the result?
Assuming the insertion of the CD won't work for you for some reason, there are a couple of things I would try:
1 - If possible, take the 80GB drive and connect it to another computer running XP Pro as a slave drive on the same IDE channel (ribbon cable) as the hard drive that has the Operating System installed on it (usually the primary IDE), and boot the computer to see if the 80GB will allow that system to boot and is recognized. If so, then we know the fault is on your Master drive somewhere (probably the "hal.dll" file mentioned by the error).
2 - Try connecting the drive on your machine to the slave position on your secondary IDE (ribbon cable), which most people connect the optical drives (CD/DVD) drives to > boot machine to see if a successful boot can be accomplished and to see if the drive is recognized and accessible.
*Note - before doing procedure #2, go into the BIOS settings and set the drive with the XP Pro Operating System installed on it as the first boot device, making sure the CD and/or any secondary channel devices are after this drive (this will be in the boot order, or boot sequence section of the BIOS settings) > save your settings and exit.
3 - You can download the correct "hal.dll" file for XP Service Pack 2 here http://www.dlldump.com/dll-files/H_1.html > overwrite the file in "WINDOWS\System32" folder > go to the cmd prompt (Start > Run > type: cmd > hit Enter > type: regsvr32.exe hal.dll (you can copy the text here if you want to paste into command line) > reboot machine to test the current file's functionality.
If all is well, try connecting the 80GB drive and test to see if you can boot successfully.
Note - I would only try #3 after all options have been exhausted, and previous to a clean install and possible reformat of the 80GB drive. You should attempt to determine which drive (or file on which drive) is causing the issue before replacing any files. I would also burn the current "hal.dll" file in you system folder to disc before overwriting it.
If you find that the 80GB drive does not boot on another machine running XP Pro, and you can access it from the secondary cable for some reason, then I would suggest moving the contents to the 200 GB drive and the format it. If you can perform a successful boot after formatting, then replacing the data would be quite easy.
Anyway, just a few things to try. 
