I will try to give you a a description of how I do my pics.
I shoot an S2, I shoot at the 4XXX size JPG, gives me a start image of 6mb
Once I find images I want to use, I use the crop tool and crop it to 8x12 @ 300 DPI - Yeah technically I loose a few pixels, but you NEVER see it !!!!!!
(That being said, I even crop 12x18 @ 300 dpi and you dont see any loss of quality on the printed image)
Then I take my 8x12 image at 300 dpi and run it thru a conversion action I spent a day writing.
The action takes the original image and turn it thru about 14 steps (4 in downsizing, 4 in unsharp masking and 2 in mode changes a couple in selecting layers etc) turns it into my finished web image. My finished web images are either 600 px tall for portraits or 700 wide for landscapes.
My borders and branding are a seperate action.
Here are a couple of pictures, I dont really think they loose that much quality in the downsizing.
Just out of interest, my final action saves for web at a 65%setting.
hope this helps,