I can confirm this (working at mega-corp) and can also add that a lot of specialized and embedded tools are primarily hosted on Windows. Even high-end CAD and modelling tools are primarily on Windows where I've worked.
High-end CAD tools used to be run almost entirely on Unix systems (Solaris, SGI, HP/UX, etc.). Back in the 1990s Windows systems couldn't handle these tools the way Unix workstations could, but once that changed there was no reason to spend far more money on a workstation. Perhaps if Linux had become popular a few years sooner the transition in high-end CAD would've been from proprietary Unix to Linux. See for instance http://www.ptc.com/partners/hardware/current/support.htm where support for various *nix are being phased out by Parametric Technology, Linux included.
Yeah, I remember those days well, we had Unix boxes for CAD and 386s with Win3 for office work side-by-side. I think you're right - the transition to Linux would have been an obvious choice if the timing had been better.
