HD-A3. Well I have my HD-A3 in a bag for portability to my parents on when we go on a trip. I try to use it every 3-4 months so it doesn't dry out.
Onkyo 805. Just received and replaced my A3. It is hooked up to my 720p DLP projector on a 94"+ 16:9 custom made gray screen via hdmi. The audio goes into my onkyo SR304 via optical (yes I know I am not getting the advanced codecs through the optical). I use it mainly for upscaling actual DVDs and the occasional HD DVD. This is more of a secondary device than a primary for me.
Xbox HD DVD #1. I have this hooked up to my HTPC. I use it load HD DVDs and DVDs onto my seperate media server via home lan which currently holds about 30 HD DVDs. The HTPC is hooked up to the onkyo via analog so that it can output the advanced codecs like TrueHD. the HTPC is purple with BD installed as well. I use Nero 8 with the HD DVD/ BD plugin. Does a great job decoding the audio. It took me a while to calibrate it to match the output of a SA player in Video, but it is set now.
Xbox HD DVD #2. I have this hooked up to my Dell 4700 (P4 2.8 / 2GB Ram / HD2600XT) which in turn is hooked up to a 22" WS LCD. I use that to watch DTV, movies over the server. I attached this drive to the PC first to load movies, but have found it really handy as I have it on my desk next to my monitor which makes it easier to load all of my disks on as I don't have to reach down and push buttons on the box. Currently looking for a few more on ebay for the other PCs in the house.
Well thats it for me.
What surprised me is how much better a HD DVD looks on my daughters 480i TV than an SD. The colors are much richer on the HDM.
Another that surprised me is how handy these xbox drives are as PC DVD drives.
I keep my media server organized to launch my store HD movies off of Xlobby 2. Pretty handy actually although for my collection. This is an older screen shot. I have alot more on there now.