Take a look at this post. It's a little dated but may help.
Also, text may display in the center of the TEXT BOX, if that's what you're using. If you're using a any other method, text as a sprite or BG image, the size of that image will effect the placement. i.e: if your window is, say, 960, 480 and your image is 113, it won't center due to the fact 113 can't be evenly dived into 960, 480.
Hope this helps.