Hi VKRISHNAKUMAR,
I think the best and easiest way is to use some partition/MBR manage software, such as "
EaseUS Partition Master"
or "
EasyBCD".
After you will remove one partition information (D drive for Windows XP) from the partition table, you can format D drive and use it freely.
Please read documents of these software with much care, before manipulate the partition table.
Regards,
Ashidacchi