Smokey house - how to get rid of smell

[Katie Maurer]

We are interested in a house that has horrible smoke smell.  It's turned the walls and ceiling a bit yellow.  I see people recommend an oil base Kilz paint for the walls and ceiling.  And to rip out all the carpet.  Also, see suggestions about using an ozone generator, anyone have experience with that?  Any other suggestions on getting rid of the smell?  Thank you!