Fluid can work, when ever I've used it, it has tended not to display properly. I always created my websites with 1024x768 resolution and have it display in a CSS container, that normally takes up most of the page. If it is viewed in something higher, then the area around the container expands. If its viewed in something smaller, then it wont work.
Good thing with fixed, is you have a good idea what its going to look like in a majority of resolutions, although IE, has a different definition to what a pixel means...