Welcome to TSF.
You cannot resize partitions in Windows XP.
Try
Parted Magic. It's a (free) live Linux CD.
Burn the downloaded file with e.g. Nero and boot the computer with the CD.
Use the partition manager on the CD to resize (shrink) the D: drive first - then expand the C: drive.
An easier way may be to use
CleanUp to get rid of redundant files on the C: drive.