If you have Windows XP Pro, Rt Click on My Computer, Manage, Disk Management. You can view your current configuration. Possibly make changes.
Additional helpful information from Microsoft - http://support.microsoft.com/kb/309000
You might also download SystemRescueCD - http://www.sysresccd.org/Download - Lynux boot disk. Run a program called GParted. This will allow you to totally control your partitions without upsetting your OS boot. A great tool we all can use.