10 easy steps:
1) Don't create a second partition - delete it!
2) Put the "RedHat" Linux Disk in the drive (CD or DVD)
3) When the install options come up press enter
4) Follow the on screen instructions
5) When it gets to the partition stage tell linux to leave existing partitions and to use the free space available - it will create a partition table for It'self.
6) Continue to follow the onscreen instructions.
7) I would use Grub as the boot loader
8) Should be about time to reboot into linux
9) Configure Grub to boot XP - There is plenty of information available telling you how to do this.
10) Reboot and choose which OS to boot.