Changing the Web Parts on the "My Site" Page
To change the web parts displayed on a users My Site the first time they log-on you just need to:
Access the "My Site" page when logged in as an administrator
Swap to "Shared View" using the drop down on the top right
Modify the page to suit, that is, remove/add the web parts as desired
Sign on as a new user and access the My Site, they should then get the view you laid out in the previous step.
Or sign on as an existing user, then using the drop down on the top right, select "Reset Page Contents".
The thing is that the "My Site" page simply behaves like any other portal Area page, you get a Shared view AND can also have a Personal view (on area pages this has to be enabled, I discussed this here: Enabling Personalisation on Portal Area pages).
The above steps simply configure the Shared view for "My Sites" which is the initial one a user views before they perform any personalisation.