If PHP is an option, you could use something like this on your Individual archive templates:
CODE
<? if ("<$MTEntryCategory$>"=="personal") {
echo "Note that I often alter or obscure names, dates, places, and other info to protect my privacy and the privacy of others.";
} ?>
and on the Category Archives, you'd just need to switch the tag to MTArchiveCategory instead of MTEntryCategory.
Then you just put this where you want the next to appear, and voila! it only shows up when that category matches.
If PHP isn't an option, then I think Kevin's
compare plugin would do this similarly - the MTIfEqual tag would go something like this (untested):
CODE
<MTIfEqual a="[MTEntryCategory]" b="personal">
Note that I often alter or obscure names, dates, places, and other info to protect my privacy and the privacy of others.
</MTIfEqual>
and again, you'd need to change the code to MTArchiveCategory for the category archive template.
Hope that helps,
Kristine