Starting with Git: Cheat Sheet
thinkvitamin.com
thinkvitamin.com
Then just type 'cheat git' and you'll have nice tidy reference for git (and a host of other subjects) right from the command-line.
cheat sheets
cheat ruby_one_liners
cheat textmate
cheat svn
cheat sql
cheat mysql
etc...
Also, it won't blind you. :-)
http://code.google.com/p/tortoisegit/
It's like permanent cheat sheet right where you need it.
The only thing is, if you can't print it(something you'd have by your desk), it ain't no cheat sheet.
Then you tell them that you have already been using git-svn for months to do your work, and the migration is effectively done already.
As someone said: "The biggest non-technical difference between git and mercurial is the rabid culture surrounding git. mercurial users fairly happily and quietly use their tool, while I've had to send two separate door-to-door git missionaries away today alone." (http://www.rockstarprogrammer.org/post/2008/apr/06/differenc...)