I'd like to emphasize what Kin wrote: resize, then sharpen. Even if you start with a high resolution image that is adjusted and sharpened perfectly for printing, you will almost certainly want to sharpen again after you resize. When you reduce the size of the image, you lose detail. There's no way around that, but by sharpening after reducing, you can often restore the appearance of the detail in the original. Sometimes a boost of contrast or saturation will help as well.
I don't know if Photoshop CS1 has "save for web" (CS2 does), but it's very handy for storing your settings. You can still do the same thing with "save as", but it's a bit more work. Experiment with jpeg compression settings. It's amazing how much an image can be compressed before there is noticeable degradation.
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