Currently, apart from several Amiga computers (3000, 1200, 2x2000), I own a C64, a C128, an SX64, an Acorn A5000, a PowerMac G3, a Mac IIci, an Atari Portfolio and a Sun Ultra 2.
And quite a few pc-boxes, but I don't count them as retro. Even though several of them are equiped with old Windows versions like 95, 98 & NT4. :-)
My computer history goes from the C64 to the Amiga 500, to a pc. Most of my retro machines have never been used by me as my main computer, but have been acquired out of interest. I would like to have an MSX 2 or something, but space is lacking...
And yes, I do count the Sun Ultra 2 as a retro machine, even though it is still quite capable with 2 GB ram, dual 400 MHz cpu and two 73 GB scsi-drives. Likewise with my beige PowerMac G3 (1 GHz cpu, 768 MB ram, 128 MB videocard & 80 GB harddrive).