any ideas where to buy or what model this is?

Dennis Wood
Cinevate: DSLR Rigs, Camera Sliders, Follow Focus and More (http://www.cinevate.com)

Dennis of Cinevate is the same guy who has made the varifocal relay for his 35mm adaptor for the SI2K. It also works with the Letus Extreme/Elite and probably the Ultimate.

do you know what the unit is above the si2k, but below the laptop? curious little thing...

It is better to mount the laptop on a separate stand or at least on the tripod's leg, not head. (I do so either way, and separate stand is always better when you can afford it.)

Mounting laptop on the tripod's head would disbalance the rig due to center of gravity being too high. This will translate to more vibration and less precise camera panning. I don't even want to think about tilting ;)

CAGE CLAMPS: Cinevate Inc. (http://www.cinevate.com/catalog/product_info.php?cPath=22&products_id=133)
PROTEUS CAGE: Cinevate Inc. (http://www.cinevate.com/catalog/product_info.php?cPath=22&products_id=113)

I would like to have this setup for some studio shooting. Or for confined spaces. Though about using a magic arm to arm it off the tripod, but have found that to be a little dodgy at times and wanted something a bit more 'robust', with no chance of slippage, or being knocked.

I'd recommend just a light stand with the small shelf on top. Your audio IO device and laptop go there, and it will adjustable and stable, and not affecting your camera/tripod system at all. Still portable. I use it.

I have that as well.
I got a 750 roller stand, and a 750 base plate with a 10x15 pancake (plywood) screwed into it. I use a bungee for the laptop, and maffer/noga arm (or velcro) for the zoom. The cinevate was just an excuse to save cable wrangling and setting up a second tripod. Nice and compact.

Mine is a standard small light stand with a custom aluminum plate I made myself. Plate houses my RME UC unit underneath, and laptop on top. I don't use bungees - instead, velcro works great for me to secure the laptop. Not too much either - just a couple of narrow strips alongside the front edge will do. (Hey, if your laptop falls, don't come suing me OK ;)

haha, yeah, i was going to do velcro also.

I have a patch of velcro on the back of my LCD and a secure my external USB hard drive to that.
I capture via USB to that 7200rpm 500gb elephant drive. I was using an external SSD drive, but it started glitching on me. - it would freeze the image for a couple seconds during recording (but not on playback) and it would randomly buffer out. NOT good when doing 1 take interviews with sensitive subjects and the DVR buffers out, having to wait for up to 20 seconds for it to clear the buffer.

what is mounted above the camera head / below the laptop?