Hi I have just purchased an all in one Acer Aspire desktop Z5761 from PC World. The advert and on line manuals state it can be upgraded to 8 MB of Ram and to do it you need to remove the chassis screws and slide the case off. There are no visible screws so I do not know where to start. 3 of PC Worlds Tech guys had a go and even they do not know where to look.