I have a couple of old Mac Mini systems, in mostly working condition. By old though, I mean 2006 and 2007 era. The older one has a single core 32 bit CPU clocking in at a blistering 1.83 GHz, and a whole gigabyte of RAM. All of that backed with a 60GB HDD. The 2007 is a little better, boasting a 64 bit dual core CPU clocked at 2 GHz, 2GB of RAM and a 1 TB HDD (it also has a defective optical drive, which is more of a problem than it ought to be – thanks Apple). Neither are going to set any records, and, of course, neither are supported by Apple any longer – the 2006 can run Mac OS 10.6 (aka Snow Leopard), and the 2007 gets up to 10.7 (aka Lion).