Arnheims general thoughts about colour and a design education strongly influenced by grey paperboard made me very careful when it comes to colour.
Especially when displayed on (uncalibrated) monitors or under varying light conditions, achieving a proper colour impression is an art by itself.
The Gnome HCI Styleguide on Colour suggests using a palette of 32 (predefined) colours and not to rely on them.
Ideal would be to make the whole colour scheme skinable via something like a simplified CSS.