Recently, there are a lot of articles talking about how business is generally staying away from Windows Vista, and they're giving all of these reasons such as compatibility, reliability, system requirements and the like, but the real reason you're not seeing the business side jump all over this OS isn't because of just these things. It's the Genuine advantage.
For example. here where I work, we had Vista running everything most office workers need; Office, IE, SCT, Even wIntegrate, which is an ancient terminal program from 96. There was three reasons we didn't go to vista. One was the System requirements we were not quite ready to meet, another was that F-secure (our virus scanning system) did not have an official Vista version at the time, but the real reason we decided to stay with XP even if all the above problems were resolved was simple. The Genuine Advantage is for lack of a better word a total pain in the ass.
In Vista there are two ways of handling corporate keys. One with a Key Management server and the other with a Multiple Activation Key. Under KMS. You are required to have a KMS server on your network, tie it to DHCP and give it your VLK (which can be changed if your old key is pirated and propagated to networked PC's). once you do that it will activate any Business version of vista automatically every 3-6 months without entering any keys, but if the computer is no longer on the network (say a Laptop) after 3 months, the system locks you out in a reduced functionality mode which can only be described as useless.
The Second method; MAK isn't much better. basically MS handles the KMS for you. this means that you don't have to worry about traveling users not being disconnected from your network for too long since it works over the Internet, but now MS is handling your activations, and you have to contact them every time you hit your quota in order to activate more windows, which isn't as bad as it sounds. According to MS activation isn't counted against your licence count, and you can request indefinitely. However, if MS sees a huge activation spike. (say your activation rate average goes from 100 a day to 10000000 a day) they disable your key (which brings us to reduced functionality mode for all MAK'ed PC's) and then you must go to each and every MAK managed PC and change the key to a new one supplied by MS.
So basically, to use Vista you either have a server on your network and pray no one's laptop cripples while their on a business trip, or you contact MS until the break of dawn and pray that no one pirates your key so you don't have to touch 1000 Crippled PC's with the Dreaded "YOU ARE A PIRATE!" message. Add to the mix that under both of these systems, your company is sailing the high seas if one disgruntled employee decides to give out your corporate key to WAREZ R'US, or if the system is completely disconnected from the network (to be used as a secure storage platform or to run dedicated equipment for example) and you got a product that companies will avoid like the plague.
As for the other excuses, Most businesses would have upgraded to vista over time. The gleaming example of this is windows 2000 to XP. There was no technical reason to go from 2000 to XP, but many businesses did it anyway over time and a service pack release. Now with vista, you got companies that are flat out saying they have no plans for vista at all and are looking at Linux and MacOSX as alternatives, and I can guarantee that Their IT dept's are most likely looking at what hell they would have to go through to appease Vista Genuine Advantage and are throwing it out the window. It would be a safe bet that if MS changed the licencing scheme for Vista from Key Management Server/Volume Activation 2.0 back to Volume Activation 1.0, (the old method) adoption would be much higher than it would be right now. Office 2007 doesn't have the "YOU ARE A PIRATE!" system built in it and still has the old VLK licencing system like XP. I can guarantee that it's adoption in business is much higher than Vista. I know we're using it here, but Vista is sitting on the shelf.
Maybe, hopefully, MS will see this and realize that the Genuine Advantage is looked at as a Genuine Disadvantage for business, is making corporate IT departments around the world look at their OS competitors and their earlier business friendly versions of windows, and in the long run, the money it's saving by stopping privacy is not worth losing the corporate business that they've established over the past couple of decades.