Just a follow-up, since I moved forward with this on my own: I checked the drive with Partition Magic and got an Error #108 (Partition didn't end on cylinder boundary!) Something nasty happened when Linux resized that partition (unless it was corrupted to begin with). Also, Freespire's Jiffyboot kept erasing the boot flag on the Vista partition every time Linux started. This did not prevent Vista from booting, but it has the effect of hiding the Vista partition from the repair tool on the Vista DVD, so I had to manually change that in Linux just before booting the DVD. (No doubt somebody else will need to know this sooner or later!) However, an automated repair with the Vista install DVD accomplished nothing. Same for a "bootrec /fixboot" - and "/fixmbr" - and a "chkdisk" repair. Oh yes, that got rid of grub, and I was hoping to install Vistaboot in its place, but somewhere along the line, this only made it worse: it froze during boot and eventually dropped to a BSOD with the error: UNMOUNTABLE_BOOT_VOLUME. So I conclude that the folks who sucessfully deleted grub with "bootrec" (of which there are many) probably did not have a corrupted partition table too.
An experiment with "Partition Table Doctor 3.5" just blew the poor thing away: after an "automated repair", the Vista & Linux partitions were merged into one large unallocated segment, and now only the Linux swap partition remains. Can anyone suggest a decent partition table repair tool which can scan the drive and find deleted partitions with operating systems installed on them? Maybe nobody cares, but I mention all of this for the sake of anyone else who goes to install another OS on the same drive without using the right partition resize tool. Microsoft seems to have intentionally made it difficult for anything else to peacefully coexist with Vista (but then again, destroying interoperability with proprietary standards has always been their game). Yes, maybe the Linux developers should have tested this more... but what reason would Microsoft have for not properly documenting the workings of NTFS, other than to frustrate the competition? All the more reason to explore other options. I confess to being a heavy multitasker, but Vista is surprisingly slow, unstable, disk intensive and memory hungry on all of the platforms I've seen (not just mine, where I push it to the limit). I hate it, and only want it around for the sake of compatibility, not for daily use. 'nuff said, I guess... but insightful observations always welcome.