Here's what I do/did: Assume the new customized dashboard  is called
"CoolGroup".

* Went to main dashboard, clicked Content, went to the news  web part,
clicked Export, put into separate directory

* Side note: I put .dwp files from the default install into a separate
directory so I can re-use more easily instead of actually using the
Microsoft web  part gallery - makes for faster and more secure import.
* I did this for just about all the sharepoint built-ins -- you don't
have to for this set of instructions, but I wanted you to know more about
what I'm doing with the web parts.
* I just go to every web part in all the default dashboards and export
them into this directory.

* Create new dashboard called "CoolGroup"
* Import that .dwp into one new test dashboard via Content->Import Web
part. Named the web part "CoolGroup News".
* Create a new directory to hold the news items. I used Windows
Explorer via the web folder for http://server/wksp <http://server/wksp> .
For example, you could create /Dashboards/CoolGroup/News. Then you have to
allow this folder to contain news item profiles. Right-click the new News
folder, go to properties, Profiles, and check "News Items".
* Edit the new web part (bring up CoolGroup dashboard, click on
Content->Advanced Settings, then edit the "Store the following data" piece
to have the first line be this new directory. Actually put in
"/Dashboards/CoolGroup/News" without the quotes.
* Add new news items into this directory, and they'll just show up on
that dashboard. Give author priv's to the right people, and they can edit
their own news items.
* Misc:

* The second line is the order it'll print in the web part. Default
is newest to oldest.
* The third line is how many it'll print. Default is "3". Make
"empty" (word without quotes) to be unlimited.
* The above steps can be done for announcements, quick links and I
believe events. I only do it for News and QuickLinks.
* If you make this new directory a subdirectory of /Portal Content,
then the "Add a link to the home dashboard" web part from the Microsoft Web
Part Gallery will work great. Useful because you can't just right-click in
a link's dir and say "New->Link".

Hope this helps, and I apologize for the HTML bullets that probably don't
translate to the list very well.