On my system VLC is not capable to disable the screen saver. Yes, the appropriate option in VLC is enabled. My computer is Windows XP but my company configured it so that the screen saver options are not changeable, even for an user in administrator mode. MPlayer is handling this issue very well and disables the screen saver without any problem. I wish VLC would do so too!
PS: I tried VLC with both 0.8 and 0.9./1.0.