The Radeon HD 4550 shows that it is no gaming card, again. Of course, you can try to achieve a higher speed by lowering the level of detail and resolution, but this would make the game less appealing visually and thus less enjoyable.
The Radeon HD 4670 and HD 4550 are both far slower than the Radeons that have a 256-bit memory bus. The 4550 model has a speed of 10fps, which is completely unplayable.
The Witcher: Enhanced Edition
The Radeon 4550 is about as fast as the GeForce 9500 GT, neither card being able to provide a playable frame rate.
As we found out in our recent review, Fallout 3 is an optimized application, yet this optimization is not enough to ensure a comfortable speed on every graphics card. So if you want to explore the radioactive ruins of the post-nuclear Washington, you have to lower the level of detail or think about buying a Radeon HD 4830 at least.