Several years ago, IBM said they would quit using Windows in their daily business. They waffled for a while, then admitted it wasn't going to happen any time soon.
Well, the time has finally come. IBM has decided to bite the conversion bullet.
Make no mistake about it; there are high costs to be paid in converting from Windows desktops to Linux and GNU software or any other scheme. And IBM doesn't get off any easier because they are a heavily biased Linux user and seller. Still, once those costs are paid, the savings will take over and reflect the wisdom of your choice forever after.
In my experience, when compared to XP Pro, Linux does not offer all that much of a performance benefit, nor a reliability benefit. That, of course, is ignoring the costs of virii, worms, etc. that plague Windows. Eventually, I'm sure Linux will have some of the same problems in this area, but for now it does not and I specualte it's more secure design may well keep it from being the stationary malware target Windows has been for many years now.
In servers, Linux often delivers a reduction in the amount of active administration needed per machine. I doubt that will carry over to the desktop realm. Users are users and some of them can screw up an anvil. Nothing is proof against these people.
Every Linux booster I know is heralding this move by IBM as the death of Windows on the corporate desktop. Nothing could be further from the truth. But it is a step in the right direction and will bring desktop Linux closer to the fore than it has been.