By "atmosphere", do you mean everyone turning up their gamma to the point that flashlights become useless? :p
I've just started my first year of college, I'm youthful and energetic and can stay up late, and television bores me (save for a couple channels), and I have no driver's license, so I'm almost always here in front of my computer. Although I have started college and will have more homework and such soon, I've still got loads of free time on my hands. Even after Halflife 2 comes out, many of us will still play any other games we've been playing. I didn't stop playing Halflife when I got Unreal Tournament 2003, and I didn't stop playing Sarcraft when I got Warcraft 3; I may be really really into the newer game for a while, but I won't completely leave everything else behind.
One thing I'm wondering though: You are getting a copy of Halflife 2 as well, aren't you?