You guys would do well to learn some basic photoshop skills regardless of software. I use GIMP most of the time, but I can only do basic stuff. cropping and resising. I ALWAYS start with a hi res photo and crop it down and re-size it. For example, if you are trying to show some detail on your engine, you obviously don't want to post a huge photo of the entire engine bay, but rather crop it down so you can still show good detail yet have a manageable sized photo.
For example, I posted to the tower project thread: