Should I request payments at freelance milestones?

I'm using Elance (I know, I know) to make some money on the side, and this is my second client. This time the scope of the project is larger, and it's expected that this job will take about 2 weeks to complete. However, in the terms proposed by the client they're asking to pay for the whole project once it's completed. Does this mean I have to send them everything first, or can they just dispute afterwards if the deliverables they get aren't what they asked for?

I don't really feel comfortable sending everything before receiving payment.