I am normally a Delta flyer but have been thinking about switching to Star Alliance. I am not sure exactly how this program works though.

I have signed up for US Airways and United preferred programs. If I fly on US Airways until I get their silver status, will my United account automatically be bumped up to the equivalent silver status? Or will I just be awarded "star alliance silver" which is something different than the United silver?

Also, do I need to sign up for a Star Alliance account or do I just need accounts for the airlines that I plan to fly such as US Airways and United?

Thanks in advance.