Other things to consider before you tear out any walls is what is in the wall, and what support is under the wall. The attic or basement can help you to see if you have any plumbing or electrical lines in the wall area. Mostly you will be concerned about any main lines.
The next thing is the existing wall load. There are live loads(you and your stuff)and dead load,the house above the wall.Make sure the beam going in can carry the wieghtand that the posts going down(king and jack studs) are landing on more than the flooring.They should have solid support underneath all the way to the foundation or a beam.
Follow the path from top to bottom.
The up side is mabey you have trusses and there is no bearing wall!!
I live on a slab two story. I have two bearing walls on my first floor and one on my second floor. Most walls run from one side of the house to the other are bearing walls but not all well run from one wall to the other depends on if you have a second floor and what is up there room wise and if you have a continuous run of your floor joints. Most bearing walls run the opposite of your trusses not parallel to them.
So if you are standing up in your front yard and can see the roof and in the back yard and see the roof chances are that any walls running left to right/right to left are a bearing wall/walls inside your home. If you are your still unsure look around the area for a builder doing a home and ask him to take a look for you when he has some spare time. The guys around here are very nice and helpful and dont charge for it when it is little stuff and they love to brag about there work (justified) and a cold one after along day goes a long way or as my dad use to say a little butter with the syrup makes a lot of difference.