My browser window is typically 950 px wide on a 1028×768 screen (so that I can keep an eye on windows off the side of my desktop, in which something dynamic might be going on).
I vastly prefer liquid a layouts — many fixed width ones use, IMHO, fonts that are too small, or else line lenghts that are too short, or make me squint by being too off-center. (But some do solve the problem beautifully, I admit.). On my blog, a scrollbar shows up at under about 780px. I’m not happy how I solved the problem (fixed width left side column, liquid content area), but whenever I try something else, everything falls totally apart in some versions of IE. (And by “totally” I mean not just boxes adapting to oversized content, but some parts overlapping others, jumping around or otherwise making a nuisance of themselves.)
On my second site https://chrysalidesque.f2o.org , I opted for total liquidity. Everything is fully readable and functional down to 600px or less. But it may look a bit left-heavy over 1028 px since I had to set a max-width for the content. I might enclose everything in a centered div, but haven’t been able to do without breaking the wrapable menu in some browsers.
If it weren’t for the IE family, both sites would long be better centered.