The standard desktop at the company I work for used to be a Sun Ultra 5, and when the company imploded I picked an Ultra 5 with a fast processor (400 MHz), put some more memory in it, took it home and put Debian on it. It worked fine. Entirely decent interactive performance, like a fast Pentium 2. Not a box for video editing or other high-CPU/bandwidth activities, but fine otherwise.
I was amused to note that it
wasn't a Windows box, so it was immune to Windows attacks. It wasn't an x86 box, so it was
immune to x86 attacks. I guess I amuse easily.
We had a pile of 32 bit SparcStations. We (literally) couldn't give them away.