As a postscript, I ended up getting a 110Mhz Sparc 5 with two 5G drives and CD. I also got a rather natty 17" Sun monitor with Trinitron tube thrown in. I put Suse 7.3 on it last night and wasn't particularly impressed so I've taken Mr. Faulks advice and will be giving netBSD a try.

Ooh, happy days, now if I can find an onyx going cheap....