are you seeing the desktop surrounded by thick black borders on all sides? so the image isn't going full screen on the lcd screen?
If so, it could be the screen resolution. Check your display settings (start>settings>control panel>display) and try different resolutions; the higher the better.
I've found that some thinkpads have "best" resolutions like 1024x768, or the newer ones that are 1400xsomething. when set to that it should fill the screen.
I think it has something to do with the lcd technology only working best for certain resolutions. when you set it to other resolutions you get either a pixel-doubled look (which is shite) or a small box, which I think you might have. Incedentally, when you plug an external monitor or projector into the back of it the notebook, the shite resolutions are outputted fine. that's why I think it's the lcd display only liking certain resolutions.
cheers,
a