One of the most difficult issues casual workers have is trying to come to grips with what they are worth on an annual basis. A lot of casual workers think they can just multiply their hourly rate by 38 hours per week, then again by 52 weeks and arrive at their annual salary. They often overlook the fact that you don't get paid annual leave, sick leave or public holidays. There is an uplift on the hourly rate to compensate casual workers for this.
Vice a versa with permanent employees looking to move to casual employment. Whilst more often than not they don't get the uplift on their permanent salary, it is still an issue that needs to be considered.
This is a link to a simple spreadsheet that may assist you in making the comparison.