You might try—just to test things out—getting rid of the Uber light and using something simple like:
a Distant Light at 30% intensity that casts no shadows
a Spotlight from the top right (position 60,200,100, Xrot –20, Yrot 30) set to 70% intensity, Raytraced Shadows with 60% Shadow Softness
(this lighting formula taken from: http://greywulf.net/tag/tutorial/)
It won’t look as good, but it should render much faster…and if it doesn’t, you’ll know there’s some problem not related to the lighting.
My computer has 3GB RAM and can render scenes with multiple characters with hair and UE2 lighting…but as stated previously, it can take up to 24 hours or even longer. Since your shading rate is 1.00 I wouldn’t expect it to take quite so long, though (I generally use either 1.00 or 0.2).