The common image of a meditator is one of a person who is seated on the floor in an upright position with his or her arms rested in their lap like when some is praying they have bended knees and their hands are clasped together. These are typical images but for meditation you don’t need to be seated on the floor. I think that in the east they tend to spend more time on the floor so it would make sense that when you meditate that you would do it in position that you are used to, likewise in the western culture we are a chair sitting culture and so when we meditate we may prefer to be in a seated position. I think if you want to sit on the floor than go ahead and sit on the floor or if you want to sit in a chair than go ahead and sit in a chair, there is no right choice. You should not feel the need to sit cross legged on the floor. I don’t like to sit cross legged on the floor because I feel that it is hard on the knees that is why I prefer to sit in a chair. The big thing is not what position you take, but that you actually start the practice of meditating on a frequent basis.