Older games run slow with newer graphic card?

Hi,
I had an old laptop Radeon 9700 64MB, 1.5GHz Centrino, 512MB RAM, and bought a new Amilio 3438 256MB Go6800, 1.73GHz single-core, 1GB RAM. It works well with new games such as FEAR, which I can run at medium settings and 800*600 (I use an external monitor 1280*1024)
But when I tried some old games (SPlinter cell, Brother in Arms, Hitman COntracts) and checked frame rates using FRAPS these ran at about 10-15fps at 1280*1024 and had to lower to 800*600 to get 25-30fps (medium settings, no AA / AF).
Just to check, I ran FRAPS on my old laptop and was shocked to discover that I was getting the same or often higher fps at 800*600 on my old laptop.
Can anyone tell me why this happens? COuld it be something wrong with my new laptop / settings or is it because new graphic cards cant handle old games well? For instance, I have heard that the Thief 1/2 series looks worse with NVIDIA 6- and 7-series cards. Is this true in general for most old games?

 

I think it may be due to the rendering. Some cards have bad rendering (Direct3D, OpenGL, etc). Maybe those games are using a rendering that isn't well implemented in your graphics card. If there is an option in those games, try and change the default rendering. I know in Half-Life they have this, maybe other games have it too.

Also its also a good idea to update the drivers if newer more updated ones exist. Sometimes notebook manufacturers put older drivers for stability reasons, thus have poor graphics performance.

Also make sure you met all the system requirements for the games: http://www.systemrequirementslabs.com

 

Check your drivers, what is happening is strange. Unless all games run slower or near the same speed on your new graphics card the older games should not run slower, the radeon 9700 don't have any special dx8 or dx7 mode and the nvidia drivers are known for better opengl support.
update your drivers, removing the old one.