Welcome to FT! It's perfectly fine to fly US Air just as any other airline. US is in Star Alliance, the largest airline alliance in the world, so you get all the Frequent flier benefits with any other Star Alliance airline, such as United.
People have been speculating about US Air (and United/Delta/American/Continental/Fill-in-your-choice-of-major-air carrier here) failing ever since Sept 11 2001. And all of the above are still around. US has the cash flow to get through summer 2005 perfectly fine. Plus today is the start of more new flights and a new "low-cost" route schedule, with emphasis on DCA, PHL, FLL, and even PIT.
see http://www.flyertalk.com/forum/showt...47#post3682847