Preloading External .swf and then some

Hey guys - I have an issue. I have an external swf file called com1.swf that I load in a MC called “comHolder”. I used the script below to load com1.swf.
_root.com.comHolder.loadMovie(com1.swf);

Here is what I want to do.

I need to know how to capture through action script when com1.swf reaches it’s end (when it has played all the way). Once I have captured that info I want to then go to Frame 2 where I have another script to load com2.swf.
_root.com.comHolder.loadMovie(com2.swf);

What it is part one tells a situation and then part two has the answers.

Thank you guys for your help.