Cannot reinstall the Snow Leopard nor install windows with boot camp

Hi

I've been having big problems trying to solve my problem. I've checked all the posts related, tried all the solutions and still I didn't get anything, so I'm sharing my problem and hope for someone to have the solution.

I installed Windows XP with BootCamp and it was working fine.
But then the HD space of the windows partition was too small and I needed more space. So what I did was erase the partition with the Disc Utility.

But before that I wanted to test the Parallels to see if the windows 7 would work fine with it. It installed easily but I didn't like the performance of it, so I just erased it with the AppCleaner.

Then I erased the BootCamp partition with Disc Utility. No problem.

But when I tried to use the Boot Camp Assistant again, it only gave me the message: "The Disk Cannot Be Partitioned Because Some Files Cannot Be Moved"

I've checked the forums and it was said that probably if I use iDefrag, it would solve my problem.

Once I did it, I still got the same message.

Then I decided to repair the dic, so I did the verification and clicked on Repair Disc Permitions and I've got this message:
-The file SUID "System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/MacOS/ARDAgent" was modified and cannot be repaired.

Then I decided to reboot the whole system inserting the installation disc and pressing the C button, but all I get is a white screen and no response. And sometimes the Macbook not even start properly (also having only the white screen and no response), so I need to press the Option button till the Mac HD icon appears and I can access the computer.

And now I really without any option and I wanted to install the windows.
Is there anyone that can help me?

 

Well, I just resetted the PRAM and when I tried to resinstall the Mac OS X, It askes to restart, and I still get the white screen.

 

The PRAM resetting did work, but when I insert the Mac OSX disc, it refuses to restart....

I even tried to hold press the Option button and the disc image appears, but when I click on it, the screen freezes.