In my IBM ThinkPad 600 there is 228 MB amount of memory. RedHat have found only 64MB of them.
This is a BIOS problem. The machine doesn't correctly support E801 memory sizing. You can pass mem=228M as a lilo option, or add append="mem=228M" to the lilo.conf for the kernel. Be sure to try this on the command line first before adding it to the lilo configuration. You may need to give 227M on some systems as some ram gets borrowed by the BIOS at times. The 2.4test tree also tries to use 0xE820 memory sizing which tends to be less buggy (vendors have to get it right as windows 9x uses E820 sizing 8))