I'll echo this sentiment with my personal anecdote:
Working for a large Canadian telecom, preparing to launch a new service, I was reviewing the infrastructure at the behest of my manager after a sysadmin had moved into another role. I discovered, with no more than 2 weeks until this high profile service was to launch, that our clustered SQL instance would behave fine while sitting there or under minimal testing load, but as soon as you piled it on, the system would outright fall over.
Long story short, this led to a 36 hour phone call with Microsoft where I was escalated to SQL engineers and Windows engineers who in turn managed to pull strings at HP to get driver engineers on the phone leading to the discovery that the HBA drivers for our servers were crapping out under said load.
I'm a proponent of Linux, I use it where appropriate, I get support from RedHat on stuff that I need support on, and I generally loathe the generic issues that come along with running Windows. That said, when it comes to "Somebody is going to lose their job if I don't get this fixed" there are few organizations I'd rather have backing me up than Microsoft.