Grub installation

I am having a problem with the dual boot.
I started with a clean system, no OS at all. I installed fedora core 3 and grub came with it. all was good. sometime later I decided to install windows XP (what was I thinking). the install went ok and Wiindows XP is working fine. the problem is that the windows boot loader overwrote Grub in the MBR. there is no dual boot and I assume Grub has been wiped out. There is just a single boot to Windows. how do I get Grub ( or any dual boot) working?
all instructions on installing Grub assume you can get to the Linux command line and file system. Any ideas on how to proceed?

Thanks,
Wireless