I have recently upgraded the memory of my machine from 2GB to 4GB, and now when I run 5.1.1 from the CD it only recognizes 3 GB of memory. Has anyone else seen this as a problem?

I have found the same situation with the last three releases of the desktop Kubuntu. Some people have suggested that this is an architectural limitation. I presume that they mean that 32 bit architectures will not support 4 GB of RAM. I suspect that the kernel build flag CONFIG_HIGHMEM4G doesn't mean 4GB, i.e., it has a bug. To test this hypothesis, I have rebuilt the 2.6.22 kernel, setting CONFIG_HIGHMEM64G as the only change to the kernel configuration and the system seems to work fine and reports that the available memory is 3.9 GB which is what I would expect with 4GB of memory. That seems to refute the architectural argument.

My machine is a Dell XPS 410 with an Intel Core 2 chip and 4GB of ram.

I hope that full support of 4 GB of ram will be considered in the next release of Knoppix.