Since you are going for images that are suitable for web viewing, you might try "save for web and devices" in Photoshop. This is what I use. Take your 8-bit PSD, convert it to sRGB, re-size to your site specs, add adjustment layers to boost the contrast and saturation, and then do a "save for web and devices." Adjust quality to compress the image so your site is fast. The point of the preview window is to replicate what the image will look like in a web browser.
Hope this helps.