I don't know if this information is allready known, but I've found a way to
change the colours of the background nebula.

Download this file and put it in the Freespace/Data/Interface folder

http://www.wild666.freeserve.co.uk/gamepalette1-03.pcx

now go into FRED and use the gold coloured nebula.

Dark
robert@wild666.freeserve.co.uk

http://www.wild666.freeserve.co.uk/