In the 90's, I did some FEA, and wound up getting asked to be a formal sysadmin for all the Unix workstations doing this kind of work in the company. I cleaned up our sprawling mess by installing a central server, making a NIS workgroup, and hosting home directories, and versioned folders for binaries. In the process, I wound up dealing with all of these machines. I have a fondness for all the OS's, for different reasons. I found HP-UX to be the least intrusive, IRIX to be the prettiest, Solaris to be the most well-supported (with the shareware site I forget the name of), and AIX to be the most sysop friendly (with their TUI admin tool that would explain the commands it was running). I've looked at buying old machines on Ebay, but apparently a lot of other people are waxing nostalgic about them too, and the prices reflect this.