Most laptops do not have a video card in the same sense as a desktop computer. They have a couple of chips soldered directly to the motherboard.
If the system is under warranty, let it be Gateway's problem fixing it. If it's out of warranty you can scour ebay for someone parting out the same system and get the motherboard if you want, but be prepared for the possibility that it will just be easier and cheaper to get a new system.
I have a mt3422 Gateway laptop and when booted it has a black screen, I have tried removing memory, hard drive, dvd drive, and cpu and rebooting with no change. I am thinking video card or mother board, doe anyone have any helpful hints for me. Thank you