As the demographic change progresses, dementia is going to become a prevalent condition in many countries. In order to keep the Quality of Life (QoL) of People with Dementia (PwD) on a steady level, Assistive Technologies (AT) implemented on table-sized Surface Computers (SC) that promote playful and/or reminiscence-triggering activities turn out to be valuable tools for dementia care. This article gives an overview over two similar multimedia-based AT systems implemented on Microsoft PixelSense SCs and field-tested in dementia care institutions. The observations indicate that both systems can trigger positive emotions and activities as well as memories.