Bootcamp error - segmented hard drive

I have a problem with creating disk partition via Bootcamp Assistant.
when i try to run it i get an error message saying "soem files could not be moved" and the process of creation is aborted.
I have sufficient free space of 50GB, trying to create 32GB win XP partition.
Some freeware utils confirmed that my th data writtne on my HDD are very fragemented (and so is the freespace).
I'd like to create a compact data area (wich would result in creatin a compact free space area).
How to do it please?

so far i've found 2 ways:
1) Backup my HDD, reinstal OS , crate a fresh partition and than copy the backuped fiels back - unfortunalty i don't have a backup drive
2) use iDefrag (a payed 3rd party utility) - unfortunalty this one has very limited usage on mounted disk, and so it has a little/no efect on my hard drive fom which i boot the system, and i don't have a second drive to boot from

what to do? is there any other solution how to reorganzie my data please?

Hey.. You can install Macosx Disk in Usb of 2GB and defrag the computer.. then install Windows without using any usb or dvd.. If you want to do this way... let me know

try this and read the comments too:HOWTO: Install and Boot OS X 10.4 On a Flash Drive | OS X Tips

To arion:

Buy an external drive, they're inexpensive. You should be making backups anyway especially if you're planning on installing Windows via Boot Camp. Use Time Machine to make the backup to the external drive, then use method number 1 in your original post. Don't waste your money on iDefrag which may not work right anyway.

Regards.