It would appear that, not-entirely-contrary to my common rant that Windows offers no text processing tools at all, Windows does offer a find command which is like a severely crippled grep.
It has five options:
U:\>find /?
Searches for a text string in a file or files.
FIND [/V] [/C] [/N] [/I] [/OFF[LINE]] "string" [[drive:][path]filename[ ...]]
/V Displays all lines NOT containing the specified string.
/C Displays only the count of lines containing the string.
/N Displays line numbers with the displayed lines.
/I Ignores the case of characters when searching for the string.
/OFF[LINE] Do not skip files with offline attribute set.
"string" Specifies the text string to find.
[drive:][path]filename
Specifies a file or files to search.
If a path is not specified, FIND searches the text typed at the prompt
or piped from another command.
So it kind of does what I want about 70% of the time I use grep, and is probably a reasonable stand in afterwards. Certainly beats firing up notepad and ctrl-F ing.
Now to find an awk and a sed…