I currently have a Honeywell RTH7000 series programmable thermostat. It broke so I bought a Honeywell RTH3100C non-programmable. I want to get some help in wiring it beforehand because I had problems wiring up the 7000.

Current wiring w/ wire colors:
blue - C
green - G
yellow - Y
orange - O/B (labeled this on terminal of thermostat)
red - R
white - auxiliary
black - E
brown - capped off

The new thermostat has:
E, Aux, Y, G, O, L, R, B, C terminals

Is the following correct in translating the old wiring to new?
C = C
G = G
Y = Y
O/B = O
R = R
Aux. = Aux
E = E
Leave brown wire capped?

Yep, the meaning of the terminal O/B probably needs to be set in the stat. If it's wrong, you'll get heat in cool mode and vice versa.