Computer Supported Cooperative Work (CSCW) is an area of computing that has been receiving much attention in recent years. Developments in groupware technology, such as MERL’s Diamondtouch and Microsoft’s Surface, have presented us with new, challenging and exciting ways to carry out group tasks. However, these groupware technologies present us with a novel area of research in the field of computing – that being multi-user Human-Computer Interaction (HCI). With multi-user HCI, we no longer have to cater for one person working on their own PC. We must now consider multiple users and their preferences as a group in order to design groupware applications that best suit the needs of that group. In this thesis, we aim to identify how groups of two people (dyads), given their various personality types and preferences, work together on groupware technologies. We propose interface variants to both competitive and collaborative systems in an attempt to identify what aspects of an interface or task best suit the needs of the different dyads, maximising their performance and producing high levels of user satisfaction. In order to determine this, we introduce a series of user experiments that we carried out with 18 dyads and analyse their performance, behaviour and responses to each of 5 systems and their respective variants. Our research and user experiments were facilitated by the DiamondTouch – a collaborative, multi-user tabletop device.