This has to do with the skin itself so you'll need to modify the skin.  Lets assume you are using "DNN-Blue" skin.  If you open up "Horizontal Menu - Fixed.ascx" look for the "<dnn:LOGIN" tag.  This corresponds directly to the login/logout button and the "<dnn:USER" corresponds to the register/profile button when they are logged in.  You can simply move that tag elsewhere in your HTML to have it appear somewhere else.  On one of my client's sites that I'm working on, for example, I've moved the login to the very bottom right and changed the text to say "Admin" instead of "Login". 

I'd suggest looking for some of the documentation on DNN Skinning to learn about the tokens you can use (which the LOGIN and USER controls are included in).

Good luck!

Thx for your answers, I will try it.

I´ll be back :-P