I've had my 20" white iMac for more than a year now. I would, I now realise, have been quite happy with the 17". The 20" is screen is bigger than I need, bigger than I can comfortably concentrate on from my position in my desk chair, so I tend to use the sides/corners for different applications and only concentrate on one corner at a time. When you add in the fact that that iMac has a compulsory minimum brightness that is too bright for me, which requires third-party software to work around, I guess you could say I've been quite unhappy with the screen of my 20" iMac. OTOH, it's fantastic for watching TV or DVDs at an appropriate distance. YMMV.