Radeon x600 Pro

I’v got a Radeon x600 Pro 256mb in my new PC.

Now I thought that it’s a pretty good card, better than the 9800 XT Pro I have in my home PC but i’v found that the 9800 will run games like BF2 and San Andreas better than the x600. On the x600 I can’t get BF2 running really smoothly on even the medium settings, especially when playing the Special Forces expansion. San Andreas can be slightly laggy/juttery even on medium settings.

Anyone know why this is? I don’t want to buy a new card, I can’t afford it, but is there a way to perhaps squeeze some more juce out of it?