No no no no no no no! Don't do that. If you ever want to use multiple blogs you'll be buggered. Use blog A, and you'll probably want a linkblog too, so leave that there as well.
Thanks a lot Graham, I used blog A as you said and it works great. I have a server with addon domains so I installed a few b2's and can experiment with one while leaving the main intact.
No no no no no no no! Don't do that. If you ever want to use multiple blogs you'll be buggered. Use blog A, and you'll probably want a linkblog too, so leave that there as well.