While importing some data today, I found myself having to convert the Roman numerals in the source to decimal. While there are scripts and tools available on the Internet to do so, a quicker way exists (or, at least, it did for my case). This solution is to simply import the data into Open Office Calc and use one of its native functions to do the conversion.
Calc provides a number of conversion functions. In this case, the ARABIC() function returns the Arabic equivalent of a Roman number as follows:
Entering the above code in a Calc cell will convert the contents of cell A1 - which is assumed to represent a Roman numeral - into decimal.
Hope this helps :)