If your account gives you the option of redeeming $25 for 500 US Airways DM Miles, then you are fine. That means the "E-Rewards Program" that you signed up for includes US Airways as a partner.

Basically, depending on who invites you to join E-Rewards, you might have a different version of the "E-Rewards Program" that has different partners. My friend was invited by Emirates to sign up for an E-Rewards account -- in his version, there is no option to redeem for US Airways, just Emirates and a whole bunch of hotels and stuff. I was invited by US Airways to sign up for an E-Rewards account, so I can redeem for US Airways miles, but maybe not for other loyalty programs.

Bottom Line: Just make sure that once you sign up for an E-Rewards account -- and before you spend months taking surveys -- that you have the option of redeeming for US Airways Dividend Miles. Otherwise, you will get to $25 in E-Rewards currency, and then wonder why you went to all the effort.