In MSCRM 3.0 you do have the ability to remove Form Assistant from a form or set it to being opened or closed when you open a specific form. However, to do that you had to modify the Site Map, not always the easiest thing to modify.
However, in MSCRM 4.0 this is now included in the GUI within the Customizations section. From Customizations, open an entity, open the Form and then click on Form Properities. The first tab you will see will be:
Now changing the Form Assistant is as simple as changing a checkbox and publishing your changes.
Things are just getting easier and easier for Administrators.
Dynamic Methods Inc.