Push tabs/knobs and while doing that push/pull/lift the cover abit. Once its loose, the rest should follow w/o holding tabs/buttons. Make sure no screw(s) are locking down that cover, it may only be one screw if any. I too many times finding opening some(any maker) cases a hassle and relearn again and again how its done, so don't be discouraged, sometime a good smack is required. Did you check with Sony support website for your model# and see what it takes, try looking for upgrade advise for replacing HD(just look) to see what they mention.
i simply just to not get it....i need tto install a new audio card on my moms computer and i cant figure out how to open the case...there are two small tabs on the back of the computer but i push them either way and nothing budges...there no screws or anything, its a mystery to me...HELP