I just made this work. Installation worked fine for me with 1024 MB of RAM in the emulator however booting took a long time to figure out that I had to lower it to aroun 256MB. There appears to be a bug in the AGP emulation from Parallels and the linux kernel only tries it when there is a certain amount of memory. This is not unlike the same problem Athlons had at one time. So use the following kernel boot parameter. mem=nopentium This will allow you to boot @ 1024MB or probably higher if you can crank it up. For background see: http://www.uwsg.iu.edu/hypermail/linux/kernel/0201.2/1535.html I'm now happily FC5ing along on my Intel Mac.
GRUB Configuration after installing FC5 and you do your first boot. Be sure to click into the parallels window so it captures your keyboard and mouse. Press "e" 2x to stop the timer and edit the GRUB entry. On the line that says "kernel" add "mem=nopentium" at the very end. Press escape to exit. then "b" to boot. It should fire right up. You can then edit /boot/grub/menu.lst and add this "mem=nopentium" option so you don't have to interrupt the next boot. Good luck!