Hi,
OK, the keys are slightly different for a new install. So backing up....
Using Microsoft Virtual PC 2007 SP1 (free download).
From VPC console:
01. Press New... to create a new Virtual Machine. The New Machine Wizard will start.
02. Press Next on the Wizard Welcome Page
03. Select Create a Virtual Machine. Press Next.
04. Name and Location; Enter a name for the new virtual machine. Press Next
05. Operating System; Select 'Other' Press Next
06. Memory; Select Adjusting the RAM, allocate 512MB, Press Next
07. Virtual Hard Disk Options; Select a new Virtual hard disk, Press Next
08. Virtual Hard Disk Location; Set required hard disk size, Press Next
09. Completing the Wizard; Press Finish.
10. Select the new Virtual Machine in the console and Press Settings.
11. Ensure the Networking setting is set to the required adapter, Press OK
12. Select the new Virtual Machine in the console, Press Start.
13. In the VM window, select from the menu: CD / Capture ISO Image.
14. In the Select CD Image to Capture dialog, select the F10 ISO, Press Open.
15. In the VM window, select from the menu: Action / Reset.
16. In the message box, press Reset.
17. When the 'Welcome to Fedora 10!' screen is displayed:
Select 'Install or upgrade an existing system', press Tab to edit options
(before the timer expires)
18. The screen will show something like:
> vmlinuz initrd=initrd.img
19. Add a space and then add to the end of the line:
vesa noreplace-paravirt clocksource=pit psmouse.proto=imps nohz=off
20. Press ENTER
21. At this point the normal Fedora installer starts.
As long as enough memory was allocated, you will get the graphical installer.
Now you can enjoy Fedora 10 running under Virtal PC 2007 
Good luck... and enjoy.