^
the screws being tight is most likely a side-effect of the heating-up the hard drive does (if i'm not mistaken). they're most certainly removeable, however you must be careful, because if you're using a screwdriver with the wrong type of head (believe me, there are LOTS of different kinds of phillips heads), you will quickly strip the screws. this will happen particularly if you're using a screwdriver which has a head that is slightly too thick, so that the tip doesn't completely fit into the screw.
the threads themselves shouldn't actually have any problem in terms of tightness, so most likely, if you have the right screwdriver, you'll just need to turn it with enough force until you get a little "pop"--that is, getting the screw unstuck.