The 'how close you can sit' rule isn't based on the size of the screen, it's based on the definition of the image. So - perversely - you can sit closer to a larger, hi-def image than you could a smaller old-styled CRT image. After that, there's whether it's comfortable or not - which is a personal thing. Jez is totes right though: the first thing to check out is any interpolation / 'smoothing' feature (or whatever the brand of set you have calls it) which often comes default set as 'on'. It's bloody horrible - made me feel absolutely sick as a dog too until I hunted it down and switched it off. On the whole, whatever size you get, most people will get used to it - and find it harder to go back to something smaller. 40 would seem too small now.