Zalia - when you say "doesn't open," what do you mean? My 2007 MBP would start up and I would hear the chime, but my display was dark. Apple replaced my video card for free after the technician found that it was the faulty NVIDIA card. However, it wasn't until months after the original problem, several trips to the genius bar and certified apple repair shops, several angry calls to customer service, and my insistence based on the apple support article that I cited to the technician. This was almost 3 years ago and I haven't had a video card issue since.
To others with this problem - I have a 2007 MBP. I had video card/display and battery issues starting in mid-2009. By early 2010 I had a new video card and replacement battery. As of about 2 months ago, my new battery refuses to hold a charge and my BIOS battery has died. Every time I unplug my computer, it resets itself to December 31, 2000. I cannot disconnect the computer from my AC cord without risking this reset. Is this a documented problem with the NVIDIA logic board? Can anyone help me find documentation so I can possibly get it fixed? Thank you!