Hello, how do you create a partition so you can install XP?
Well, the quick answer is "Use Device Manager to create a partition in unused space on one of your drives."
However, I suspect that the quick answer is useless to you.
Michelsmith offers XP mode, which is probably the best thing to use unless you absolutely have to boot into XP rather than using XP mode.
With dual-boot systems, it is well-established that, if you want to boot two different Windows versions, you should install the earlier versions first. Otherwise, the boot manager of the earlier version (in this case, XP) will overwrite the boot manager of the later version (in this case, Windows 7) and leave you unable to boot the later version. Not a good situation.
Plus, keep in mind that userids will be different in your two installs. Sharing data between them will require either a scalpel, to create ACLs for both systems on the same data, or a sledgehammer, making all data world-write.
There are a number of solutions if you want to continue with dual-boot. Read on if this is the case.
1) Buy a new disk. Install the new disk in the system. Unplug all the other hard drives (really). Install XP on the new disk.
This may be the simplest and safest configuration. Once XP is installed, you will have two bootable drives. Use the BIOS to select which drive to boot from.
2) You really, really want a new partition on an existing drive. Find a drive with freespace and create a partition. Back up your Win7 OS drive, in case this process destroys your ability to boot Win7. Install XP. Make sure that it runs. Note that you can only boot to XP at this point.
Now, boot to the Win7 DVD and choose to repair an existing installation. It will find your Win7 installation without a Win7 MBR and bootloader, and repair it. You will be able to boot Win7, but if I had to guess you will not be offered the option to boot to XP. If you are offered this option at this point, let me know and I will learn something.
Now install and run EasyBCD. Read the directions on the site and create an entry to boot your XP.
3) Give up on your current Win7 installation. Re-partition your OS disk with new, empty partitions for XP and Win7. Install XP and make it happy. Then install Win7 on the other partition and make it happy.
Believe it or not, a lot of experienced people will choose number 3.
Please let us know what your considerations are and we can advise on which is the best route for you.