Well this is a tough situation. Old laptops are the hardest to update properly due to the hardware having /extremely/ short driver maintenance lives

ususaly, you can get the drivers for the original OS the laptop shipped with but nothing else 99% of the time.
But, you can get the video chip number from the computer specs or possibly form the hardware manager and look on line for a driver for it for Windows 7. May be another laptop manufacturer has had the same hardware in a newer laptop with a Windows 7 driver and you can get it from them, or if your REALLY lucky, from the chip manufacturer themselves.
If that utterly fails, you can go for broke and try installing the XP driver. Now this is generally BAD ADVICE as there is every chance that that will 1) not work at all or 2) wreck your windows 7 install, but since it's a new install, and if you have no other options, you won't have lost anything if you end up having to reinstall 7 or XP after it fails anyway :/