Thanks to Stan :) for taking the time and effort to respond to my post. I found his suggestions really useful.
I was able to flip to a console in F14 and successfully login to my user account, but sadly I never resolved the graphical login issue where F14 kept redisplaying the user login screen after I had entered my password. I did check the log files, but wasn't able to google much from log file text.
Anyway, have re-installed Fedora 14, and it seems to be working fine now.
The major learning was to make sure that grub is set up correctly asap, prior to doing lots of work on the linux install.
I have a dell laptop and the first non-boot partition is a Dell windows recovery area, so Vista is on (0,2). The default grub.conf setup is set to (0,1), so I edited it as soon as I was able, without letting the Vista boot-up fail. Now I can successfully dual boot and have had no problem with the user login screen on F14.
Barry.