Hi alisaalthaus. Welcome to BleepingComputer
Let me guess what you have been doing : you started Windows 98, inserted Windows XP disc and started to install XP. Then computer restarted and you cannot choose partition. Problem is that in this manner XP setup copies setup files on C: drive and you have only one partition so you cannot choose any partition. This way XP can be installed in dual boot mode along with Windows 98 for which you need at least two partitions.
This is what you can do :
1. Start in Windows 98. Backup all your important documents to an external disc like pendrive, USB hard disk, CD or DVD.
2. Insert XP disc. Cancel the XP setup if it starts. Restart your computer.
3. Choose to enter BIOS settings (by pressing Del
in most cases) and make your CD as first boot device and Hard disk as second boot device. Save settings.
4. Your computer will be started again. Now you would see Press any key to boot from CD....
. Hit any key on your keyboard and proceed.
5. In Windows XP setup when you reach the point to choose a partition, choose C: and then choose to perform full format as NTFS.
For full step-by-step XP setup instruction, see the following links :
XP Home clean install : http://www.theeldergeek.com/xp_home_install_-_graphic.htm
XP Professional clean install : http://www.theeldergeek.com/xp_pro_install_-_graphic.htm
If you get stuck at any step, feel free to ask here