I have a Dell Inspiron 8200 Laptop and am using Instlux from http://instlux.sourceforge.net/ to install Ubuntu 6.x.

One issue I had was when I booted into the Instlux menu and pressed enter to start loading the kernel I got an error message saying it can't mount the partition. The Grub for NT boot loader configures the kernel and initrd at hd(0,0). However rebooting into windows and using disk management it displays a small dell utility partition as hd(0,0).

The fix was to edit the boot loader to have the kernel and initrd at hd(0,1) this fixed the issue and I was able to start the install process.