Power Mac 7500. Started with a 100 MHz PPC 601, 500MB HD, and 16MB RAM. Ended with a 375MHz G3 (with a couple of 604s along the way), 20GB HD, and 384MB RAM. Learned Mac programming with CodeWarrior and Java with MRJ. It ran BeOS, MkLinux, and Mac OS X Server 1.x flawlessly.