XP has no contingency for partitioning unused file space in a partition.
Note: Windows, including XP, calls a partition, a "drive".
If MVPs and other "volunteer" supporters in this newsgroup fail to provide
that above more clear information, don't consider that an oversight. Its
been consistent for over a decade regarding MS's term for "drive" and
others' term calling same a "partition" being ignored entirely. For what
purpose other than a MS politico origin, I don't know. If that's not the
case, despite my observations in the past decade, inform me otherwise... If
I hear a consequential silence or MS politico responses, I consider my
observation as valid.
What you need is 3rd party software that has the ability to create a
PARTITION from unused file space within an existing partition. I don't
recommend it as windows, and especially XP, need some free file space to
operate within most 3rd party softwares needs. I won't go into swapfile
needs for free file space, as its PC dependent and swapfile use dependent,
and RAM dependent. In short, don't want to start a long, and, something
that's been gone over again and again in this newsgroup. Unless you have
boatload of unused partition file system space, get another physical hard
drive. If that is the case, give more info.