=> XP installed on D: drive, How can i change to C: drive?

My operating system is installed on D: drive. I want to change it to C: drive. How can i do that without loosing any data?

i've win XP SP2. My all hard disk partition are NTFS.
THIS IS MY HARD DISK CONFIGURATION:
C:>> MY DOCUMENTS+MY PICTURES (1 GB OCCUPIED+10 GB FREE SPACE)= 11 GB
D:>> WIN XP SP2 INSTALLED ((system, boot) (1GB OCCUPIED+3 GB FREE)=4 GB
E:>> DOWNLOADED FILES+GAMES (5 GB OCCUPIED+6 GB free)= 11GB
F:>> SONGS, MOVIE (4GB OCCUPIED+ 7GB FREE)=11GB