C-a'ing emacs and screen

I spend my days in screen, emacs, irssi, and various Mozilla apps.  I'm pretty happy, but one that that drives me crazy is that C-a (i.e., CTRL+a) is "go to the start of the line" in emacs, and also how you invoke screen commands.  So running emacs in screen means you lose C-a.

Not any longer.  My current build and analysis cycle is close to an hour, so I have time to do things lower down on my TODO list, like read the man page for screen:

C-a C-a (other)       Toggle  to  the  window  displayed  previously.  Note that this binding defaults to the command character typed twice, unless overridden.  For instance, if you use the option "-e]x", this command becomes "]]".

C-a a (meta)          Send the command character (C-a) to window. See escape command.
Happy day!  Ted says he can't believe I don't know this, but it's one of a million things I have yet to learn.