||Top Ten Digital Photography Tips|
Response to: Picture Resolution
if you use Macromedia Fireworks MX and go through this route File\Export there should be steps to save your image at web quality. Also, there is a function through this route to specify the file size which you want.
If you use microsoft photo editor and go to save as, select .jpg then click on the "more" button and select the quality manually. 50-70% is good enough.