I guess the decision to provide IE6 support depends upon whether you're designing commercially or not. I can't turn around to my clients and tell them that 25% of visitors potentially won't see their site because I no longer support IE6. I do add targeted notes to sites though encouraging upgrades. IE6 will just die a natural death in the same way 5.5 did, patience is required...
800*600: with the growing number of mobile / semi-mobile devices and mini notebooks, small dimension figures are increasing. No one can realistically afford to ignore this market sector.
