I am having trouble figuring out the wiring for a new programmable thermostat installation.

I moved into a barnd new house equipped with two Robertshaw Model 9400 Thermostats (one for each zone). I bought Honeywell RTH7500D programmable thermostats to replace them because I wanted programmable thermostats. I have two central AC units (one for upstairs, one for downstairs) and I have a gas furnace.

The curret thermostat is wired with the following:
Red Wire > RC (Jumped to RH)
Yellow Wire > Y
Green Wire > G
White Wire > W
Orange Wire > O
Blue Wire > B
There are also a brown wire and a black wire not used coming out of the wall.

The new honeywell has the following connections:

Conventional --- HP
C --- C
G --- G
Y --- Y
W --- O/B
RC (jumped to R) --- RC (jumped to R)
R --- R
W2 --- AUX
Y2 --- E
--- L

Any ideas on what wire goes to what? I can't figure out the orange wire and the blue wire and I don't know if I need the brown or the black.