I'm amazed these quotes haven't been mentioned, but maybe the game's just too old for most people to remember.
"Look at you, hacker: a pathetic creature of meat and bone, panting and sweating as you run through my corridors. How can you challenge a perfect, immortal machine?"
"You travel within the glory of my memories, insect. I can feel your fear as you tread the endless expanse of my mind. Make yourself comfortable... before long I will decorate my home with your carcass. "
The Many: "Do you not trust the feelings of the flesh? Our biology yearns to join with yours. We welcome you to our mass. But you puzzle us. Why do you serve our mother? How can you choose cold metal over the splendor of the flesh? But you fear us. We hear your thoughts, and they rage for your brothers who you believe dead. But they are not. They sing in our symphony of life. We offer another chance to join us. If you choose to lie down with the machine, we will rend you apart, and put you separate from the joys of the mass."
The lines in that game seriously chilled your spine to the core. God I miss it, think I'll go back and play the first one.