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.

You only need one *A account (US, UA or other), and can collect miles from all *A carriers with your program.
In general, I would suggest to use the account with the carrier you fly the most.

Most alliance frequent flyer programs work in the same way. So generally speaking, whatever you experence with Delta (as part of skyteam) you are likely to experience as part of star alliance.

With your delta program you build and maintain stauts on Delta, which can then be used for benefits on other skyteam airlines (but you get the MOST benefits on Delta).

Same applies with star alliance, or oneworld. The carrier you achieve status with is likely to give you the most benefits (those which are applicable to their members only), but there are shared alliance benefits such as priority check-in, baggage and lounge access.

Some of the exclusive benefits for the airline you accrued status with might include upgrades, upgrade certificates, bonus miles, or access to preferred seating.

Once you get status with one airline they send you a new card which will have a silver or gold logo. This identifies you to other alliance member airlines.

If you get Silver on US Airways, your United account will still remain the same as it was before. However, your Silver status on US Airways gets you the corresponding benefits on all the airlines of the Star Alliance (*A) network.

As jefi99 says, you only need one account from any of the members of *A to earn miles on their network. It doesn't necessarily have to be US Airways or United, it can be any one of the members' programs, whichever suits your needs better.

For instance you can get Gold status with less miles on Air Canada or Turkish Air, and if lounge access on domestic US flights is what you want, membership on one of the non-US members is what you want. For flight awards though it's cheaper to get awards on the airline whose program you are a member of.

While you already have the US Airways and United accounts t should be fun comparing them with other members programs. As a reference you may want to check out BlondeBomber's Star Alliance Gold Chart and the Star Alliance Silver Overview by FLYGVA.