WDWNovice,
You don't way where you are flying USAir from or through. Whether they are on time will depend which airport you are going out of, or where you make a connection. However, I can tell you, if you are flying from Philly, beware of baggage claim in philly on the return. Whenever I am on a flight they ALWAYS say my bags will be at carosel A (for example) and then at the last minute announce the carosel is now the furthest one across the airport. Try getting quickly through baggage claim with kids in a stroller. FUN! Also, the timeliness of USAir's delivery of bags in Philly leaves a lot to be desired.
As for MCO, I found their bag delivery time to be about average. However, USAir baggage claim and ticket counters are about as far as possible in MCO from the rental car area.