User interfaces generally rely on a main menu for navigation and orientation. Therefore, the main (navigational) menu layout design is a determinant of user performance and satisfaction levels. Effective menu designs also help users avoid feeling lost and disoriented when seeking information or finding functionality. Research on menu design finds that an understanding of users' ability to recognize a menu layout through positional and semantic grouping of menu items helps explain design effectiveness and user preference. Our research compares an expandable index menu layout design to a frame-based (dashboard) design, and finds that the positional and semantic groupings of the frame-based (dashboard) design were preferred. Real clients using a live system participated in this study using the Think Aloud usability evaluation method. This research is significant in that it contributes to ongoing work in development of effective user interfaces, and in that it strengthens the findings of earlier researchers.