European VAT number / sales tax number validation

Hello all I am currently working on a European ordering system for a piece of software. I stress the word 'European', as customers living in Europe who state their VAT/sales tax number are entitled to purchase this firm’s software without having to pay for sales tax. Now, the questions is, does anyone know of a way to: Step #1: Check the syntax of a European sales tax number Step #2: Check to see whether it really exists and belongs

        to the company ordering the software.

I know step #2 is quite a tall order, but any help with step #1 would be greatly received! Thanks. Stefen _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com.