Aparentemente (de este fórum ):
Xp has inbuilt ability to scan and OCR docs.
This ability was licenced from Xerox, despite the fact that every scanner uses it's own ocr program much better than XP built in generic hit or miss form
If you are determined to use the inbuilt XP version, if your scanner will let you, it will use the Xerox/nwwia folder as tempory holding place for the files while it processes them.
It is perfectly harmless so leave it alone.