git-checkout older revision of a file under a new name

I have the file “main.cpp” open in my editor.

I want to see the previous revision of “main.cpp” in the editor too.

The way I do it now is like this.

close "main.cpp" in the editor

prompt> mv main.cpp tmp
prompt> git checkout HEAD^ main.cpp
prompt> mv main.cpp old_main.cpp
prompt> mv tmp main.cpp
prompt>

open "main.cpp" and "old_main.cpp" in the editor

Can it be simplified, so I don’t have to close “main.cpp” in the editor?

What I’m hoping for is a variant of git-checkout that can do this.

UPDATE: im using git on mac osx 10.5.7

prompt> git --version
git version 1.6.0.4
prompt> 

UPDATE2: Jakub Narębski answer is:

prompt> git show HEAD^:dir1/dir2/dir3/main.cpp > old_main.cpp
prompt>

UPDATE3: Karmi’s answer, for a specific revision:

prompt> git show 4c274dd91dc:higgs/Higgs.xcodeproj/project.pbxproj > old_project.pbxproj
prompt>