grub won't let me in without the floppy

[PJW]

I have XP pro as the main OS.   I installed fedora on my 2nd HD.
Everything seemed OK.  I rebooted, and all was well.  I updated fedora,
and when I rebooted, it stopped at GRUB, with the screen locked up.  I
now have to boot with the floppy.  The XP is now not available at all. 
It seems the MBR has been changed as even when I unplug the 2nd HD, it
still hangs at GRUB.  
Also any suggestions of a good place to learn LINUX?  Books, website's 
lists.  
Thanks, Phil