There are a few things that need to be underlined.
Like Awatto mentioned, you should create a directory in /mnt
and then mount to that directory.
Now, is your windowsXP using a FAT32 or NTFS file system.
If you don't know, open a terminal window and type:
If it is a FAT32 file system, type:
mount -t vfat /dev/hda1 /mnt/windowsXP
If it is a NTFS file system, you will need to download and install the NTFS support RPMs.
You can also mount it automatically by adding a line to /etc/fstab
NTFS support is Read-Only.
Do NOT write to NTFS from Linux.
It may corrupt your NTFS filesystem.