As another bonus your input on sound system specifications and color preferences could end up in the final model. To seal the deal, the sales person offers you a significant discount once the car is released. So who needs windshield wipers? You convince yourself it hardly rains in Seattle and drive off the lot.
Now back to reality, or in your case, the office. Whether dealing with a giant like Microsoft or a small startup, all software companies are very eager to find customers who are willing to undertake a similar adventure with their near-to-market products. This is commonly referred to as a beta program.
The program offered immediately prior to the final release is usually run by sales and marketing, sometimes referred to as an early adopter program. This is targeted at potential customers who are looking to try out a product, but are not willing to deal with the roller coaster ride of a tech preview or beta program. The goal here is to build a solid general availability sales pipeline so the product can be marketed as a must-have, high demand item.
Sandwiched in the middle is the beta program, which is mostly driven by product management with some input from the sales team. This is a more stable release than the alpha and is offered to a broader range of customers with a formal feedback mechanism. The product can still be buggy, but must be stable enough for release to selected end users, not just techies. A successful beta program results in case studies and can prime the pump for a successful early adopter program.