I went back to this and took 4 hours of HA to go with the 2 hours of RGB in the original image and am pretty pleased with the processed result. Not a patch on What Martin has just posted but I am very pleased with it although I have lost some of the other colours in processed the HARGB
All subs at 600 seconds, ISO 400 on a Canon 30d
http://astrob.in/full/19628/C