I had a similar experience. I forget the exact timing, but it was probably around 2002 - 2003 that Linux felt "good enough." I was at a startup that finally considered putting its "enterprise" stack on Linux.

Later in 2003, when I joined CERN, there were still Sun workstations being used, and I was an earlier user of Scientific Linux in 2004.

Afterwards Nokia Networks were still deploying into HP-UX, and the first big Linux project started around late 2005, to Red-Hat.