I would really appreciate your input for this as I rework the design of my Irish gift shop. Currently my site has a standard 100% width, which sounds ok but comes with a few problems. A lot of the pages have very little content to pad it out, so it looks very very lateral. Pages are bare looking, with single lines of text looking lost amidst a sea of white space. My thoughts are to narrow the design and use white space to the sides to 'frame' my content. How does that sound? Also, if you know of any stores that have a clean and clear layout please list them for inspiration!
Just my $0.02, but I think it looks better at 1400 x 1050 than at 800 x 600. White space in the middle of the page is more appreciated by me than at the edges. To look at a successful store, try eBay. Not pretty, but successful. My only question is, why is the main font so small? You're using 8 and 9 point. Try 9 and 10 at a first step. And try larger up to 12 point for your headers. In an image editor compare a screen print of the font on your pages to a screen print of the font on an eBay page.
I think in your case fixed-width would work better (as it appears to be what you're using now) and as mt.bum suggested increasing your font size would improve the overall appearance as well.
I personally much prefer fluid designs. eBay also use fluid design for all there site except the index page.