I imagine that these might possibly be changed with some styling options. But as far as default values go, these are taken from my version of Excel 2010 which should have the defaults.
"Bad" Red Font: 156, 0, 6; Fill: 255, 199, 206
"Good" Green Font: 0, 97, 0; Fill: 198, 239, 206
"Neutral" Yellow Font: 156, 101, 0; Fill: 255, 235, 156