It will show up fine as a second drive. The only issue is if you had a password on the account you want to get files from. Those files won't be accessible without removing the password first.
Ex. : J Smith user account on XP has a logon password
T Doe user account on same OS has no logon password
All of T Does My Documents folder will be accessible on the new machine but none of J Smiths documents will be visible on the new machine.

To remove a password from XP you need a utility specificaly to remove paswords from XP OS. Do a Google search if you need such a program there are several out there.