Recently, Greg Leake (Senior Director Developer Platform at Microsoft) performed a series of IBM written benchmarks. The results of the benchmarks demonstrate a significant cost savings of running WebSphere on Windows on HP Blades as opposed to running the same workload on IBM's Power 570 hardware. This savings is not only significant but the overall performance in terms of transactional throughput was significantly better than on the Power system. In addition, the tests show the ability to scale the overall system in a granular fashion. The net findings of these tests is that an organization has the possibility to run their WebSphere application workloads on Windows on Intel based hardware for markedly lower costs with improved performance as compared to Power systems. You can find an overview of the work at http://www.websphereloveswindows.com/.
For more in-depth information on the studies, check out http://www.microsoft.com/windowsserver/mainframe/whoknew/, as well as the information found on MSDN around the .NET StockTrader Sample Application. And you can find Greg Leake’s blog here.