Status_203 - 9:46 am on Jan 5, 2012 (gmt 0)
I agree with the position that larger screens and tablets (& phones) will push the need to accommodate lower resolutions again. I'm on 1600xsomething and expect to be able to accommodate two windows side by side. A site that has essential stuff past 760-770px is already a reason not to come back (unless it is absolutely irreplacable). Scrolling sideways is more of a pain on the desktop than on a tablet!
And despite the disclaimer in the OP, (and despite the fact that my own sites currently use fixed width designs ;) ), I'll still say that a fixed width design is in most cases doing potential visitors a disservice for the sake of the developer's convenience. Which puts you at risk of a competitor coming along and doing it better.