Don't feel bad about using old equipment.
Even is research, we often run on old 486s, 386s, 286s, ... no I'm not done yet, as I've seen folks' expensive equipment that can only communicate with the old 8086s... and have even seen an Apple IIe around. About fifteen years ago, some guy even broke out his old Osbourne. It looked so sci fi us younguns (at the time) that we had to fight back giggles.
I mean, when your funding is tight, you go with what you have if it still produces good results.
In fact, those old DOS dinosaurs are EASIER TO USE AND TROUBLESHOOT, especially if you still have your old 5.25" floppies with the source programs!