What setting should I use to reduce “grainy” images when taking pictures with my digital camera?

I have a Panasonic Lumix DMC-FZ7 and I noticed that most pictures (in doors most of the time) come out grainy.
What is the most optimal setting to prevent this?
Here is a list of specifications for this camera:
http://www.steves-digicams.com/camera-reviews/panasonic/lumix-dmc-fz7/panasonic-lumix-dmc-fz7-review.html

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