Do you see this effect when you actually post the photos on your website or just in your photo program? I do rudimentary editing (like stepping down resolution) with my Kodak software and I have noticed that unless I view an image at full screen the "stairstep" effect is really evident on anything smaller. When I print them (at high res) or upload them to my website - the effect is gone.
Perhaps Anne could help with this one - she is a retoucher!
I don't have any trouble printing the photos after jacking up the DPI in photoshop. I crop to the image of the frame and send it off to our tweaky at 72 DPII to be posted. I am not familiar with "anti-alias"ing.
When you are making a marquee selection with the selection tools (oval, magic wand, or lasso tool – except rectangle marquee), there will be a check box near the top of the window just below the menu bar which will allow you turn on and off the "anti-alias" feature. A check mark will turn the feature on.
Anti-aliasing "blurs" just the bordering pixels by a smidgen so that when the box is checked, the selection edges will be 'softer'.