IBM iSeries or Windows server?

Rabid Cougar asks: "I am the network administrator for a small manufacturing company. Our current ERP system has outlived its usefulness and we are in the process of selecting another package. Our present ERP system runs on an IBM AS/400, but there are those in the company who believe we should switch to something that only runs on Windows. My position is this: if we can find software that will meet our needs that runs on an IBM iSeries (new name for the AS/400) then we'd be certifiably crazy to move over to the Windows platform. A co-worker insists there are a ton of reasons to avoid the iSeries like the plague. I'm not trying to start a flamewar, but if you were to bet your career on this issue, which side would you choose and why?"