You will have to parse all the files in C:\ProgramData\NCH Software\Inventoria\Items. Each .dat file is an item in your inventory and each field for that item is separated by a "&" in the .dat file. Each field for the item has the format:
<field-name>=<value>
Maybe create a program that parses the .dat files and generates an XML file.
By the way, "C:\ProgramData" is a hidden directory.
Hope that helped,
Gunner