Not sure you can enable it. It is there or it is not.
Hello and welcome to LQ.
Every generation of system has issues. That time frame may have been pae issues.
Not sure what you mean by doesn't look right with pae forced.
Example of how some systems may work on older hardware.
http://linuxmint.com/rel_rebecca_cinnamon.php
Booting with non-PAE CPUs
To boot Linux Mint 17.1 on CPU which do not officially support PAE (Pentium M processors for instance), please use the "Start Linux Mint with PAE forced" option from the boot menu.