HP "support". Customer wanted Windows SBS2011 on his new HP server, so I checked the compatibility matrix on the HP website. All OK.
Server arrives, drivers disc states "suitable for Windows Server 2008". Hmmmm. I call HP tech support for advice, and they tell me that server model is not supported for SBS2011. Being a suspicious type, I'd saved the URL for the compatibility matrix page, and I read it aloud to the service tech, who proceeded to remain silent for several moments. He then admitted that the situation was beyond him, and escalated to the call. I finally got someone from 2nd-level support tell me to "just try the 2008 drivers". Great, so they hadn't actually tested this machine with this OS.
Don't even ask about installing SBS2011. OK, I'll tell you. I had to pick apart the installation scripts and run some of the commands separately to make it work. When I called the supplier for help, they quoted me AUD$1400-$1800 PER DAY for a Microsoft specialist. When I pointed out this was an installation issue, and they had a responsibility to provide support, they didn't actually laugh, but they didn't help, either. Don't buy HP, and don't trust Microsoft "partners", either.