Do you need to have completely different forms for registering and logging in? If so how do you determine which form to show the user?
You are rite about how you could get them both on a single page, you would use some if statements to show one versus the other, but how do you make this determination?
Alternatively you can create a different set of user pages with the Security Assist wizard. Please post back with some more info about how you will have this setup and we will help you out with whatever we can.