This paper presents a simple vintage model that incorporates the idea of the diffusion of new technologies. As a first attempt we use a macro-economic inspired distribution of technologies which are embodied in new equipment. The speed of diffusion depends on expected profits and on accumulated knowledge. The choice of the initial labour intensity stems from the behaviour of firms, however. From our estimation results on Dutch data for the enterprise sector it appears that the speed of diffusion has an impact on the average labour productivity of newly installed equipment such that the productivity paradox can be explained. Due to a decrease in the speed of diffusion in the late seventies and eighties, the growth of the average labour productivity declines whereas the labour productivity growth of the most advanced technologies proves to be stationary during the estimation period from 1960 to 1988.