Hey Stu,
I think you've transcended beginners status when it comes to capturing, so it's time for some tough love on the processing front
I'm not sure about your latest PhotoShop repros - the background seems clipped to black quite badly (space is never completely black!).
Your sombrero is a wee bit green (try the Photoshop HLVG plugin). You may also obtain some good results by using layers by blurring the color information using a Gaussian blur, but not the luminance information and then merging the result again. I don't use PhotoShop so I'm not sure what the correct naming is for the layer modes - maybe someone else can chime in?
The way you're going you'll be posting in the Deep Space section in no time!