The only way you can create, delete, resize or merge existing partitions,
and not harm your existing Windows installation, is to purchase and use
a third-party partitioning program such as Partition Magic 8. http://www.powerquest.com/partitionmagic/
The alternative is to perform a "clean install" of Windows XP:
A couple of ways to do this.
1. Boot with your XP CD, deleting all partitions, reinstall XP to a clean disk
..
2. Acquire a 3rd party partition manager such as BootIt NG, Partition Magic, or Norton's Ghost.
You can partition on the fly without losing any programs already installed.
Use lots of caution here. Some laptop makers put a first partition as
hidden one containing part of the bios, touchpad drivers, and access to
sound elements here.
Another hidden partition may contain the entire XP installation files.
Check with your laptop maker first.