Me too....
When I got my Early 2008 Mac Pro in early 2009, Windows 7 hadn't been released yet and XP was still 100% viable, so I installed that on the second Boot Camp disk (this was before I had enough RAM for VMs to be viable) and used it when I wanted to do something that I couldn't do on Mac OS X at the time (I had software that was Windows only, and Mac versions didn't yet exist).
I did try upgrading to Vista "because I could" (I had the setup DVD from an eMachines tower that decided to die the summer before during a heatwave), and it was actually OK, especially after SP2. I still liked XP better though (and the software I wanted to use didn't run quite as well on Vista), so I rolled back to XP more or less until it went EOL in 2014, at which point I had bought a copy of 7 and upgraded. I subsequently went back and forth between XP and 7 once I learned about the POSReady2009 Windows Update hack for XP, and then I even tried Windows 2000 as recently as 2015, shortly before (or immediately after) I upgraded to an Early 2009 Mac Pro I had upgraded to 2010-standards.
I use mostly macOS now (and of course my Skylake PC can't run XP natively, although 7 does, and it runs fantastically), but I still keep a VM with each version around for fun.
c
When I got my Early 2008 Mac Pro in early 2009, Windows 7 hadn't been released yet and XP was still 100% viable, so I installed that on the second Boot Camp disk (this was before I had enough RAM for VMs to be viable) and used it when I wanted to do something that I couldn't do on Mac OS X at the time (I had software that was Windows only, and Mac versions didn't yet exist).
I did try upgrading to Vista "because I could" (I had the setup DVD from an eMachines tower that decided to die the summer before during a heatwave), and it was actually OK, especially after SP2. I still liked XP better though (and the software I wanted to use didn't run quite as well on Vista), so I rolled back to XP more or less until it went EOL in 2014, at which point I had bought a copy of 7 and upgraded. I subsequently went back and forth between XP and 7 once I learned about the POSReady2009 Windows Update hack for XP, and then I even tried Windows 2000 as recently as 2015, shortly before (or immediately after) I upgraded to an Early 2009 Mac Pro I had upgraded to 2010-standards.
I use mostly macOS now (and of course my Skylake PC can't run XP natively, although 7 does, and it runs fantastically), but I still keep a VM with each version around for fun.
c
