For Git Bash

If you are running msysgit (I am assuming you are) and are looking to run Git Bash (I recommend it over TortoiseGit, but I lean to the CLI more than GUI now), you need to figure out what your home directory is for Git Bash by starting it then type pwd (On Windows 7, it will be something like C:\Users\phsr I think). While you're in Git Bash, you should mkdir .ssh.

After you have the home directory, and a .ssh folder under that, you want to open PuTTYgen and open the key (.ppk file) you have previously created. Once your key is open, you want to select Conversions -> Export OpenSSH key and save it to HOME\.ssh\id_rsa. After you have the key at that location, Git Bash will recognize the key and use it.

Note: Comments indicate that this doesn't work in all cases. You may need to copy the OpenSSH key to Program Files\Git\.ssh\id_rsa (or Program Files (x86)\Git\.ssh\id_rsa).

For TortoiseGit

When using TortoiseGit, you need to set the SSH key via pacey's directions. You need to do that for every repository you are using TortoiseGit with.

I've had success installing Ansible (and subsequently running a playbook) onto a new Vagrant guest with the following bash script (tested with Ubuntu 13.04):

#!/usr/bin/env bash

export DEBIAN_FRONTEND=noninteractive

apt-get update -qq
apt-get install -y make git-core

if [[ ! -d /home/vagrant/ansible ]]; then
    # Install Ansible dependencies.
    apt-get install -y python-mysqldb python-yaml python-jinja2 python-paramiko sshpass

    # Checkout the Ansible repository.
    git clone https://github.com/ansible/ansible.git /home/vagrant/ansible

    mkdir /etc/ansible

    echo "localhost" > /etc/ansible/hosts

    source /home/vagrant/ansible/hacking/env-setup
    echo "source /home/vagrant/ansible/hacking/env-setup" >> /home/vagrant/.bashrc
fi

cd /srv/vagrant
ansible-playbook playbook.yml