www.tinypic.com is a very useful site for displaying photos on forums.
You upload your photo onto their server and use the html code produced to display the image in a post. Couldn't be more simple.
You can resize your photo with the website also but its better to do this yourself to reduce upload time.
I believe also that as the photo is stored elsewhere it reduces the load on the local server.
Some forums require you to do this now.
Just a thought.
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