If your cat has 100% free-reign of the house (she walks on counter tops, furniture, laps, kitchen tables, etc), you might want to consider retraining her before you have company or keeping her confined during the visit. Many guests are uncomfortable seeing a kitty trot across the counter, hopping over the bowl of potato chips and sniffing the freshly cooked ham.
Cats can be retrained in a variety of ways to stay off certain surfaces. Read PetPlace's How to Keep Your Cat Off Tables and Counters
for more information. If you don't mind having your cat in these places, and you do not want to retrain her, it is probably best to keep Kitty in a bedroom or another secluded location during house visits.