OK - lucky I DO have all that techie knowledge buried inside.... a total newbie would never have guessed...

Well I finally found parted - partition editor - it's buried elsewhere than it is in Fedora...

Reformatted the ext4 partition to ext3... and wiped all the existing partitions so we had a clean install...

Why ext4 default for Fedora? Well if you have disks that are umpty umpteen terrabytes, then you NEED it, well Linus , the father of linux uses it so he must have big disks... er, um.... most OLDER boxes - the selling point for Linux, have disks 500Gb or smaller anyway....

And then the penny dropped.... Ubuntu 'helpfully' mounts the partitions when the install fails so you can look and play with them.... you need to have them UNMOUNTED so the install can happen - fixed that and Zip!

Did the basic security installs and wow! not all there yet and the 64 bit stuff for things like image like opera plugin for Firefox etc are not available yet, but apart from the colours - red yuck, blue , (fedora) nice... and the close window button being on the left instead of the right, much bette, much faster. The basic system on install even handles most of the web formats without hunting around... nicer!
Still need to build and reload all old files for owner of PC so she is happy.... ;-)