Please post back a screenshot of your latest maximized Disk Management drive map with listings showing all columns. Use Snipping Tool in Start Menu.
Post another screenshot of the Xp Device manager with unknown devices expanded, using the Print Screen button then pasting into Paint to save and Upload. Screenshot with Paint
I would work from the Support Downloads webpage for the computer model to try to ascertain which drivers are missing, then install them if there are XP downloads to install, or search device make/model for XP drivers using Google.
To determine with certainty what exactly is an unknown Hardware Device in Dev Manager, use this tool to find the make/model and google it for XP driver, or post back for more help: Hardware Identification