I mainly collect old UNIX workstations (non x86 processors) particularly Sun and SGI workstations. I also have a lot of 8 bit microcomputers although the only one(8 bit) im really working with right now is my Color Computer 3 and Color Computer 2 which you can see a picture of on the floppy disk thread.
as far as the UNIX workstation hardware I still use it as my primary desktop. I'm retiring my Sun Ultra 10 as a spare. I havent gotten round ot making my SunBlade 2000 my router yet so the Ultra 10 is still running.
my first non PC unix box was a tadpole SPARCBook 3GX which is a nice portable laptop that is a lot like having a portable SPARCStation 5. with a 110Mhz sun4m processor (I think its a TurboSPARC, or a microSPARC cant remember), I then inherited a much slower and older SPARCStation 2 which is a 40mhz sun4c, at the same time I got a new desktop at a satrtup company around 2002 it was the Sun Ultra 10 that I use as my main desktop. they were given to us by Sun to work on a project for them.
the Ultra 10 was one of Sun's first 64 bit desktop workstations back in 1998 before most people even thought of 64bit desktops. DIGITAL beat them to the punch with the alpha CPU but Sun is still around and digital is not.
that Ultra 10 was fast enough to do most of what I wanted until recently. and I got me the SunBlade 2000.
the blade 2000 came on the market in 2002 I have the 20th anniversary edition version of it. it can take up tot 16GB of ram if you use 4GB DIMMS it has two 1.2Ghz UltraSPARC-III+ processors with 8MB of cache per processor, a crossbar memory bus so that both cpus have fast access to memory at the same time., internal fiberchannel disks, ultra wide scsi internal and external, two firewire 400 ports, 4 usb ports, extdernal FC-AL over copper connector, two serial ports one parallel port. one 10/100 ethernet port and a quad fast ethernet card with four additional 10/100 ports. I have an XVR-500 framebuffer installed which is a fairly fast for its time 3d card with nice 3d and 2d accerlation based on the 3d labs wildcat chip. the machine can hold up to four framebuffers. and for diagnostics and for remote control has full serial console support. if you unplug the keyboard while booting the firmware will work through the first serial port. and you can see very detailed diagnostics through the serial port, stuff you wouldn't see on the screen if the system was in really bad shape. the firmware is OpenBoot which is an OpenFirmware imeplementation. (people with Macintosh computers should recognize Open Firmware as thats what the PPC based macs used)
even though this box is from 2002 (last sold in 2004) I would say it competes in speed with a similar clocked PC of today certainly gives my AMD Sempron box a run for it's money.
when I buy used equipment I tend to go for stuff that used to be the top of the line this box cost over 34,000 new from sun. i got it for around 1k and it should last me for many years to come since Ive found it really hard to kill Sun hardware in fact all of the equipment Ive listed above that ive used over the years I still have and it is in working condition. except for the tadpole which has a failing backlight on the TFT screen.
It's mostly the PC equipment that fails on me. which is why I prefer to use commercial Sun hardware with Solaris for my desktop. I know that the hardware will be fully supported by the operating system and that it will be built to last. no playing guessing games and installing the patch/firmware of the week for this particular weird chipset and having to track down drivers for everything I have.
so if a 2002-2004 workstation is retro I'm definitely working retro.