No Operating System Workstation.
I had a workstation built for me at a local computer store and specified "no operating system". They said, "OK, but we will not test the machine beyond POST." I took delivery and installed ubuntu and it has been running happily ever since. Saved the cost of a Micro$oft operating system.
The only issue is having all of the peripheral drivers in linux so I only chose slightly older disks, dvdrw etc. I had no problems.