Money can buy happiness, yep. People who aren't malnourished are happier than people who are.
See, there's this thing called "diminishing marginal returns". Up to a certain point, definitely, the more money you have the happier you're going to be. A roof overhead is great, clothes that aren't filled with fleas are dandy, and a hot meal is probably the best pick-up you can get. However, after a point, money stops making you significantly happier. Whether you can afford that vacation or not doesn't really make you more or less happy. Once basic needs are taken care of, you have other problems to worry about.
You know, it's the same as Maslow's hierarchy of needs. Money can buy the bottom two layers -- it can get you food and keep you warm, it can buy you insurance and a house in a nice neighborhood. True, it can't buy you respect or confidence or love, but by that point, money's already helped you enough.
That so many people here say "money can't buy happiness" says most of us are well off. Then again, we could have probably made that assumption because we all have internet access, hey.