In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce4 MX 420 are noticeably better than the Nvidia GeForce 6150 SE 256MB.

The 6150 SE was released over three years more recently than the GeForce4 MX 420, and so the 6150 SE is likely to have far better driver support, meaning it will be much more optimized and ultimately superior to the GeForce4 MX 420 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 6150 SE has 192 MB more video memory than the GeForce4 MX 420, so is likely to be slightly better at displaying game textures at higher resolutions. This is supported by the fact that the 6150 SE also has superior memory performance overall.

The GeForce4 MX 420 has 1.3 GB/sec greater memory bandwidth than the 6150 SE, which means that the memory performance of the GeForce4 MX 420 is marginally better than the 6150 SE.

Both the GeForce4 MX 420 and the GeForce 6150 SE 256MB have 2 Shader Processing Units. The two GPUs are based on different architectures, but deliver an equivalent shader performance. To compare, we must continue to look at the memory bandwidth, Texture and Pixel Rates. In this case, we sadly do not have enough data in this area to complete the comparison.