Ashem,
If I am understanding you correctly, you would add the URL for Notes to either a custom portlet in the user portlet or add an icon to the page header, but either should be sufficient. If Notes is on a separate server, they would have to login maybe, but that's all. Technically speaking, I think that adding an icon to the page header (say, next to Help and Logout) requires changing the adp for the page and creating the icon.
I hope this answers your question.
DeeDee
