Yes, true as far as getting to the cause of an issue in a forum, the issue is most often vague or incomplete information. I like the standard litany, as opposed to coaxing information from people.
Now as far as tools that one may try for a non-booting system, I personally build and use PE UFD, or CD but many people only have access to the standard Vista recovery stuff on the CD (if they even have one). Of course with careful use that can often suffice.
If you can get to a command prompt and at least see the disks with diskpart, that's a start.
That's often the question with these things, what is the first thing to try based on the initial problem given.
Often it is, use tools to gather more information and report back. Then the user goes along using the tools and/or commands until they tire of it all and reinstall Windows, or success, lol.
But getting back to the missing or corrupt, it does sound worth it to at least rebuild the BCD, and maybe use a disk like the Super Grub2 Disk or something else to bypass the Windows MBR code to see if you can boot using alternate means.
For XP, you could use a boot floppy or even a boot CD with Windows native boot files, and apparently for Vista also - http://www.multiboot....uk/floppy.html
If no floppy, I guess the Grub works, any other nice boot CDs (not recovery) for Vista / 7 or a way to create one that boots a system?