I don't think plaintext automatically fixes the ? problem. Those are Microsoft's "Smart Quotes." They're not HTML friendly characters.
If the above fix doesn't work, you can strip them out of a document using Find/Replace. Just turn off that damned AutoFormat function first:
Word 2003: Click Tools | AutoCorrect Options | AutoFormat As You Type
Word 2007: Choose the Office button in the top-left corner | click Word Options at the bottom of the window | select Proofing in the left pane | click AutoCorrect Options | AutoFormat As You Type. (Yay for annoying graphical upgrades to that make things
harder to use!)
Uncheck "Straight quotes" with "smart quotes," and "Hyphens with dash", click OK (twice in Word 2007).
Once that crap is turned off, do a Find/Replace All on your document:
Find:
" Replace:
"
( Single quote on both.) This will replace all the smart quotes with the straight quotes again.
Find:
^= Replace:
-
( ^= is the code for those damned dashes. This can also be found if you open the More | Special menu as EnDash.) This'll fix any dashes.
You can then paste-as-text straight from Word: no need to bounce it in to Notepad first.
Ordinals paste to plaintext fine. Converted fractions will show up as ?'s too, if you have any of those, but those are usually uncommon enough it's faster to just fix them as you find them.
If you've got a ton of formatting you want to preserve in the document, lots of bold and italics, that you don't want to go fix manually you can just paste-from-word after making those two replacements. It'll work just fine, and is faster if you've got a lot of docs to copy over that you don't want to re-format.
It just makes the source code so dirty. ;_;