Dell Inspiron 1720- video card for Windows 7?

The other night I installed Windows 7 on my Dell Inspiron 1720. I keep getting a message about the video card. How do I know what kind of video card I need? Also, if you know, are the video cards really hard to install in this laptop? We have done things like hard drives in this but never looked for the video card yet. Any tips would be appreciated.|||You need to download video card driver from Nvidia , its using Gforce8400M