I am trying to set-up Outlook such that when I reply to a message by noting
my own comments against those of the originator (in the original text),
these are automatically highlighted and shown in a different colour. I know
this is possible as I use the feature on another PC.

I have tried: Tools - Options - Preferences - E-mail Options and then ticked
the box 'Mark my comments with:' but this has made no difference.

Any ideas?

I am running Outlook 2003 SP2.

Many thanks.