It is not clear what computer model and year you are trying to install XP on but there are no XP drivers for newer hardware.
And, if you are not using Boot Camp Assistant, perhaps finding a more appropriate forum than the Boot Camp forum to post in may produce quicker and better responses.
Windows still needs a MBR and Disk Utility alone won't cut it that is the one area where BCA or another tool is needed.
If you wipe the entire hard drive and format it as MBR even then I have not seen a successful install on a dedicated hard drive in a Mac Pro tower.
XP also will not align properly on an SSD.
Why go through this? can't be cost because Windows 8 RP is here and free.
And can't be because the Mac doesn't meet the requirements.
XP is without support even from Microsoft and Vista SP2 has reached its EOL.
First step is backup everything.
Next step is backup everything again, somewhere else.
I formatted the "XP to be" partition as DOS.
Inserted XP disk, and reformatted the partition. Pay attention here that you do format the correct one.
Should this reformat fail from the XP disk, you need to either use Disk Utilety to:
Format it in Mac as ExFat and try again.
Format it in Mac as Windows NT Filesystem (NTFS 3G) (this is an addition to Disk Utility you can download for free) and try again.
Hang the machine in T mode on a Win machine and look for the partition and reformat it from there, disconnect and now use your XP DVD to install. (Not sure if this would work over USB, might need FW)
Use a Win7 disk to format the partition (somehow this is a bit more clever software, is what I did, borrowed one).
Once partitioned, install XP. That was it, now boot in to XP, go through ±3 hours of updates and bla.
When finished either install the Bootcamp drivers from your Mac DVD, be ware they might be out of date if your Mac is older. Otherwise in XP go to the Apple WWW and download and install the Bootcamp drivers.
Be ware that Apple no longer supports XP as a Bootcamp software. Mine runs fine, but it is no longer supported.
I suspect that the slowness I experience when I switch OS, is due to this. Read here my other post about this.
Oh did I mention Backup first?