I generally up load mine to Photo bucket first and then copy the [img][\img] info across to the thread.
Much like Bob I also resize before sending the images to photobucket and try to keep the width of the image no larger than 800 pixels. That way I find I get a nice sized image that doesn't require scrolling across the screen.
When I convert the files to Jpg in Photoshop (Elements 6) I do have the option to compress the files down and generally aim to keep them about the 300K mark.
Hope this helps.
If you want to edit any of my images to demonstrate points/techniques to either myself or others please feel free to do so.
Still learning with Canon 40D, 28-135mm, 100-400mm L and Elements 6.
Any Advice greatfully received.