Note: This assumes that you have done the default installation of Windows XP which takes up an entire primary parition and puts an NTFS filesystem in it.
For resizing QTParted can be used. QTParted is available on the web for free of cost and by itself but it is also included in the set of applications of several Linux distributions (free of cost as well). We will be using the version of QTParted that comes with the Knoppix 3.3 CD (and in other versions of Knoppix).
For questions or suggestions email me at arodr059@cs.fiu.edu