that's a fair old assumption to make, you know.
if i were installing windows somewhere, i'd make sure the My Documents had its own partition (also known as D:\ under DOS/windows) because after getting into the habit of making /home its own partition, it's only sensible, and to use a command prompt to change to c:\ from there you would actually need to type "c:" into the prompt.
anyway, the question is a trick question because the Documents and Settings directory is only present in a windows NT filesystem (unless you created it yourself) afaik, and so if you are using an NT system, there is no DOS there, you are probably using cmd.exe which is a microsoft command interpreter designed to look like the DOS box in windows 3.11 (and other versions), which really was DOS. cmd.exe doesn't even accept all the real DOS commands, and i think it might even have some of its own. so while its interface can be said to be based on DOS, by the looks of it the program is not DOS at all.
i'm sure you're all really interested to know that... :-D