An Open License from Microsoft is a good choice if your company is just starting to work with Microsoft and you only need five licenses. There is a mandatory two-year commitment, but the flexibility of the “pay as you go” licensing model gives start-ups or emerging companies room to grow without having to overpay for licenses you don’t use, upfront.
Open Volume- provides deeper discounts when purchasing larger amounts of licenses. In order to qualify for volume licensing, you must meet a minimum point purchase level of 500 – which is determined by software product mix and license quality you plan to purchase. An example of what the point value system could be- MS Office Professional is worth 2 points, while Windows server is worth 15 points. For a full list of point values, visit the Product Licensing Web site at http://www.microsoftvolumelicensing.com/userights/.