I have Intel (R) Core (TM) 2 Duo CPU E7400 @2.8 GHZ with Intel (R) G35 express chipset.
I want to know equivalent Nvidia graphic card. what is ram capacity of this card whether Napolen total war can run with card.
If you have PCI-e slot available, enough powersupply horsepower and big enough case any Nvidia card with PCI-e interface will work.
Otherwise the integrated graphics is equivelant to FX5200- GT6100 both having pixel and texel fillrate of 1GB/s which is awful. And thanks to the Intel's weak driver support, you'll have even more performance issues. Furthermore, the slower RAM you have the slower texture load your integrated GPU will have. I bet you have PC5300(667MHz) or PC6400(800MHz) main system memory, which isn't fast for a framebuffer, it's okay for main system memory, but not good for being part of the graphics memory on IGP.
Just get a graphics card. You'll need at least GT6600 from Nvidia or Radeon HD2400 from ATI.
Recommended graphics adapters are: GT8800 from Nvidia or Radeon x1800 from ATI.
Oh yeah, you'll need at least 256MB of framebuffer(videocard memory) which i'm not sure your integrated graphics has.
Personally I'd recommend getting a weaker newer era card, you can find these things under 100€ and with 1GB of framebuffer, but don't go too cheap.. 25-50€ cards are for killing fly's or your regular entertainment(HD movies, presentations).