Edit This, Look At That. You need to set up multiple viewers, generally by locking one.
It's really easy in CS5.5, but if you are working in an earlier here's the help from adobe about it:
http://help.adobe.com/en_US/AfterEffects/9.0/WSCF40A9D1-B832-4bc8-B4B2-636C...
Johnny Cuevas, Editor
Thinkck.com
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.
