I have two hard drives installed on my PC.

on the primary one .. hda > windows xp is installed
i installed FC4 on >hdb ... however when i reboot the system the GRUB screen never appears and the system automatically boots XP.

Can anyone help me get around this problem.

Have never done dual-boot on separate drives, but this thread might offer some insight:

http://forums.fedoraforum.org/showthread.php?t=60411

Your grub.config has to be setup properly for Linux to boot; post it here to help with troubleshooting.

Ok here's what grub.conf looks like

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd1,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/hda
default=1
timeout=5
splashimage=(hd1,0)/grub/splash.xpm.gz
hiddenmenu
title Fedora Core (2.6.11-1.1369_FC4)
root (hd1,0)
kernel /vmlinuz-2.6.11-1.1369_FC4 ro root=/dev/VolGroup00/LogVol00 rhgbquiet
initrd /initrd-2.6.11-1.1369_FC4.img
title Other
rootnoverify (hd0,0)
chainloader +1
~
~
"grub.conf" [readonly] 20L, 669C 1,1 All

Your default is 1. Remember that they start at 0, therefore your current default OS is the XP installation. Change it to 0 for the first OS on the list(fedora) to become default. I would also increase the timeout.
Happy computing, Kurt