the intab file is just a way to hard code in a TEXT ONLY ( 3 ) or gui ( 5 )
BUT just assuming that it worked on fedora 12 then it will work on fedora 13 is very very wrong
Fedora changes SO MUCH between versions that only sometimes an " upgrade" works
and to use the better "preupgrade" option your /boot partition must be bigger than 800 meg ( 1 gig will do ) not the 100 meg default size .
it is recommended to do a 100% full clean install
reformat the partitions that have fedora 12 on them then let the fedora 13 installer repartition them to ext 4 .
also fedora CHANGED the version of Xorg in the default install of 13 to 1.8
Most old legacy nvidia & ATI cards DO NOT support 1.8 .
only nvidia newer than gforce 5 and up are supported
ATI ??? i do not know
also fedora 13 sets the opensource nvidia nouvea driver as DEFAULT and the open fglrx for ati
please READ the fedora 13 release notes and install guide