This paper explores, if computer support provides benefits beyond facilitation, one of the keys to success in GSS environments and one of the possible explanations of inconsistent GSS results. The analysis is based on an empirical study of 40 meetings with 360 participants in the Hohenheim CATeam Meeting Room. Teams of different size worked on an experimental task under one of three working conditions. They had either full computer support, a structured and moderated meeting process including manual support tools or no support at all. This experimental design allowed the isolation of the impact of computers, a structured intervention in the meeting process by a facilitator and an increasing number of meeting participants. Results show that overall the introduction of GSS into meetings has stronger effects than merely facilitation or moderation without GSS support though the type of effects differs for the observed variables. As most important effects which computer usage introduces to meetings an increased perceived speed of the meeting process and stronger anonymization as well as more directness of the participant contributions were identified. Facilitated structure improves task understanding, reduces dominance of meeting participants and enables teams to stay focused on the issues at hand. In consequence computer supported meetings are especially worth their additional effort over moderated meetings, when speed and anonymous as well as direct input are more important to meeting success than equal participation and a straightforward discussion among meeting participants. Moderators should consider adding computer supported meeting tools to their toolset.