This is easy as PIE!
Install Windows XP on a Primary partition, leaving however much room you want for linux as free space. Then boot from the linux install CD and Open Suse or any other linux worth its salt and the installer will suggest using the free space as linux, install itself and set up a boot loader GRUB or LILO. Done. Then whenever you boot you will have a choice of Windows or Linux. A child could do it these days. I've been dual booting Linux and Windows since the ~ 1991 or so. It was more difficult back then. Now it is a snap.
It isn't hard at all.
Note if you need to share files between the two systems, make a separate fat32 partition as it isn't safe to write to the NTFS from Linux.
You do realize that the XP kernel doesn't play nice with Linux.
The XP Kernel couldn't give a poop less about the linux on the hard drive, it won't even read it.
pcgeek