My son has a Sony VAIO Pentium 4, 2.4 GHz. It has 512MB RAM installed, but 32MB is used for onboard video. I'd like to buy him a video card for Christmas. Just wondering how to open the case. I don't see any screws on back. Must be some kind of snap fasteners. I don't know the exact model number but can probably get it if necessary. Can anyone tell me how these cases are opened?