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?

 

please keep your offensive talk o yourself
i have my ESSENTIAL data backed up safely on multiple drives
however i don't have enough space to back up ALL of my datas ...
yes it's cool, to have a time machine agree, but in my land, harddrives with the size of several TB simply aren't growing on trees nor are they given away for free...
so please stay on the topic - how to create compact data/free space