The first thing I noticed about RH 6.1 (both with the ISOs and the RH disk) was machines that have always correctly noted and handled my memory no longer knew how much memory I had. To fix this you modify /etc/lilo.conf (preferrably before upgrading otherwise you get to reboot) with the following line (with your memory size)added to both "image=" sections and then issue the "lilo" command to activate it. append="mem=256M"