Help plz-L4D not working correctly

ok, so when I launch L4D demo, it gives me a message about how my video driver is not up to date. I am running on a laptop, so I go to HP's site (cant download straight from nvidia). I download the latest driver update, install it, and restart my comp. still gives me the message. it says my current driver is #blablablawhatever, but that is the newest one on HP's site.

it wouldn't be a big deal, because I can just hit 'continue anyway'. problem is, the film grain effect isnt showing up (yes I changed it in options). I think it's a cool part of the visuals, and would like to play it with it on, but I can't. any help?

l4dmaps.net seems to be a lot less populated than this site, so I figured I would use this site

I got my drivers updated, but I still can't get the film grain to work. Am I thinking of the wrong thing? is the film grain effect while you're alive? can anyone else see it when they play?

Well, I tried it on a different comp, and I can tell that the film grain is not showing up on mine compared to other comps. I don't know why. I cranked the film grain to the highest on my computer, and there is no film grain. you can see the film grain on the other comp.

help plz?