Need some video settings help please.

Just got a new desktop. I have a Radeon 7850 gpu (old pc had a 9800gtx). My color (brightness/gamma) is all messed up and I cant figure it out. My old desktop was fine. Now when I'm playing in Act3 I have to crank the gamma (in-game) up alot so its not super dark. And if I'm in Act2 in the sand I have to crank it way down so its not just a solid gold sand color...really bright.

Im not super technical anymore on PCs, I used to be but lost all the knowledge many moons ago. When I'm on my desktop using internet or movies the brightness is fine. Ingame it goes all wonky. What do I have to tweek with so the brightness is good for all Acts?
Edited by NeonMonkey#1147 on 2/27/2013 3:32 PM PST