In terms of overall gaming performance, the graphical capabilities of the AMD Radeon HD 4290 are very slightly better than the Nvidia GeForce 6600 GT.

The Radeon HD 4290 was released over three years more recently than the GeForce 6600 GT, and so the Radeon HD 4290 is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the GeForce 6600 GT when running the latest games.

Both GPUs exhibit very poor performance, so rather than upgrading from one to the other you should consider looking at more powerful GPUs. Neither of these will be able to run the latest games in any playable way.

The Radeon HD 4290 and the GeForce 6600 GT have the same amount of video memory, but are likely to provide slightly different experiences when displaying game textures at high resolutions.

The GeForce 6600 GT has 15.2 GB/sec greater memory bandwidth than the Radeon HD 4290, which means that the memory performance of the GeForce 6600 GT is slightly better than the Radeon HD 4290.

The Radeon HD 4290 has 40 Shader Processing Units and the GeForce 6600 GT has 11. However, the actual shader performance of the Radeon HD 4290 is 18 and the actual shader performance of the GeForce 6600 GT is 6. The Radeon HD 4290 having 12 better shader performance is not particularly notable, as altogether the GeForce 6600 GT performs better when taking into account other relevant data.

The GeForce 6600 GT requires 48 Watts to run but there is no entry for the Radeon HD 4290.