Ghosting is a visual effect seen on screens, normally with high refresh rates (which is the length of time taken for a pixel to competely change colour). So higher is worse, and the MacBook has 24 milliseconds, which is pretty high.
Ghosting looks like there is a short trail behind moving objects, especially when there's high contrast between the colours. It looks like an on-screen object is bleeding colour behind itself, and it's annoying if you notice.
Re 13.3 inch: I've got a nice 17" 1920*1200 screen on a less nice Dell laptop, and I'm looking out for a new MacBook, hopefully in alumini(yes i)um.
But 1280*800 is a little daunting, and even though I've been to the lovely Apple Store and seen such wonders as Spaces and Exposé, I'm still a little worried...
Although the resolution is a cause for worry, I'm not really bothered by the 13.3 inch size, 4 inches shorter and 40 less cm^2. What matters to me is that I can still multitask to obscenity ^_^ . For which Spaces and Exposé should provide.