I can book a flight on USAir for $3200 (PHL -> Barcelona). I can book the same flights using a Spanair codeshare on Orbitz for $2800.

What would be the disadvantage of booking the USAir flight using the Spanair codeshare? I can save $800 (for 2 tickets). What if something goes wrong? Will USAir help to re-ticket, or will I need to deal with Spanair?

Anything to worry about?