Free DVD decoder

My computer didn't come with a decoder to play West Wing DVDs; I don't know why, as it plays other DVDs without a hickup. When I looked at how to get decoder software, you can download a variety of 'em for ten or fifteen dollars. Or you get lucky and discover the VLC player. The only downside is that it is it's own program; other pay-for decoder software will work with Windows Media Player or whatever, whereas this one just plays your DVDs, so whatever, cool enough.