Greetings.

This is a puzzling report.

I have a 64-bit Dell 1545 with 4 Gb ram and Knoppix 7.6.1 automatically realizes
and provides a 64-bit kernel which recognizes all the ram. Its a Win7 machine, so it
uses Legacy boot, not uefi.

You might see if you can Legacy boot your machine and get around your problem that way.
I know Win8 Dells have both legacy and uefi boot choices; maybe your machine does as well.

Hope that helps.