It easy to convert to ntfs go to Start > Run > type cmd and press enter
at the command prompt type:
convert C: /fs:ntfs
(assuming C:\ is your windows drive)
You will receive the following error message:
Convert cannot gain exclusive access to the C:\ drive:, so it cannot convert it now.
Would you like to schedule it to be converted the next time the system restarts (Y/N)?
Select yes restart the system and the conversion will take place.
You can read the Microsoft article here:
http://support.microsoft.com/kb/314097/
But make sure your read this Microsoft article before your convert!
http://support.microsoft.com/kb/822800/en-us