What kind of work do you do on that machine? I have that exact screen size and resolution and I have used ones that are 1024x768 and there is basically no room for anything. With 1400x1050 I can have two code windows side by side, or a large interface from something like GIMP or OO up at the same time as a document. 1024x768 feels like living in a small, small box, never seeing enough information to get any work done.
Probably doesn't help I have dual 1680x1050 displays at both work and home