Introduce new cat to an old cat?

[Michael]

we got a cat a last week who is a 2 year old femal(tuxedo cat) and the old cat which is a femal and five years old(orange tabby) doesnt really like it that much today is the first day we let the new cat out of the room we kept her in and when they saw each other the old cat puffed up and was growling and the new cat was growling but they didnt fight they were staring at each other growling for about an hour... this is alot better then i expected because i thought the old cat would attack the new one but is there anything we can do to get them to tolerate each other so we dont have to keep the new cat locked up