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Yes, I've used Windows 2003, but it doesn't scale like Solaris, nor remain as stable over time. It's certainly nowhere as mature in its drivers and modular architecture either. And it lacks a lot of the secondary support structures that are easily bolted onto Linux.
As an out-of-the-box solution for a homogenous network it is okay, but not as powerful as the other two when it comes to more "real world" heterogenous setups.