Not alot you can do by the sound of it.
Sounds like a vid card / driver issue, you can experiment with different driver versions, go to
www.nvidia.com
Sounds like you got a good graphics chip I dont doubt its capable of running SH3 with 16km, only trouble with laptops that I can think of - is that they no longer have dedicated graphics memory, instead they used Turbo Cache where it uses the main memory - not sure if it has something to do with that. How much RAM you got in total? if you got 2GB then I really dont think its a hardware problem. at the end of the SH3 is 2 year old game, are you running Vista or XP Btw.
if worse comes to worst -stick to 8Km.