Using this step by step ‘how-to’, you will be able to test how well your Moodle installation would be able to cope with a certain amount of users, using the loadstorm.com service. Whilst this is not a perfect representation of what real life usage of your Moodle installation would be like, it will still give you a very good idea of whether your system is good enough to run Moodle for your expected number of users.