Turn on Track Changes (Tools menu or double-click TRK on the status bar).
You can select the color on the Track Changes tab of Tools | Options. If you
are using Word 2002 or 2003, you will by default see insertions underlined
and deletions in "balloons" in the margin, but you can disable the balloons
if you prefer to see deleted text struck through (which is also the default
display in Normal view).
