Windows Datacenter Servers are certified to a specific hardware platform and those boxes approach mainframe level uptimes. Look at the Unisys ES7000 as an example. It has mainframe level redundancy and reliability and scales to 32 CPUs and 96 PCI slots. In testing I am familiar with, it smoked an E10000 in every category.
Ewwww. Let me repeat that: Ewwww.
You are using the ES7000 as the paragon of performance?! It is a monstrous piece of crap. Just so you know, I don't have kind words for the E10k either (decent architecture, really slow processors), but the ES7000 is pure garbage. For most interesting applications, it has no purpose. Color me dumbfounded that you would even bring up such hardware. It is a PC on steroids.
Cluetime: Show me a comparison against REAL hardware, not half-baked crap and uselessly narrow benchmarks. The first time Windows will run on genuine scalable architectures is when Microsoft releases a 64-bit Windows designed to run on Opteron systems in ccNUMA native mode. Yeah, its coming, but they've got exactly nothing now. If you want to fan the flames, Linux has been supported on 256 processor SSI on large-scale ccNUMA for a while now, not on an abomination of a 32 processor UNISYS system. Egads.
You have no concept of system architecture nor what constitutes real scalability. And fancy hardware is no substitute for quality OS software, which was my real point in the first place.
Bull, find me a vnedor that will give you 5 9's on a windows server. Certification means nothing if MS or any other company wont put their money where there mouth is...