dual boot partition size adjustment

If the partitions are in that order on the hard drive, you have to shrink the partition of D: from the start point to the right, and expang the first partition from the end point to the right. In any case, you have to reboot into windows at least 2-3 times, to allow the system check the filesystem.
For the second resizing operation (expand the vista partition from the end point), you need to have the "round to cylinder" parameter unchecked, to leave the start point as is.
However, I'm not sure if you need to check this parameter active for the resizing of the xp partition. I would think rather yes.

You can use the latest stable GParted livecd for these operations. Please, take backup of any important files before proceeding. There is no problem in most cases, but in case of problem it is better to have a backup rather than not.

(Moved to the live media section)

shrink the partition of D: from the start point to the right

Not from the right, but from the start of D: (left) to the right. So, the unallocated will be between the 2 partitions.
Note that this operation (changing the start sector of a partition) can be much more long than changing the end sector.
It is better to run defrag 1-2 times before proceeding. It can help to avoid errors in some cases.

Resizing the end from the right is for the c: partition
(all this, assuming that c: is located first on the hard drive and d: follows. If it is the inverse, of course, the operations will be else. The fact that a partition is named c: in the windows registry doesn't mean that is always the first of the drive.)

In case that D: is a logical partition, you need to resize the extended partition that contains it too. Extended partitions aren't named in the windows disk manager. GParted shows all with numbers.