If you've got a solid handle on IT (in general) then this isn't terribly complicated, it can be time consuming though. One of the most frustrating parts is making it all fit. At least I've got that part figured out...LOL.
Regarding laptops...there are a few guys on the CF forum that use a laptop as their carpc. I gave this a thought when first starting my process, but the problem that I ran into was that laptops only have one video out. I couldn't do the type of multiscreen setup that I wanted with a laptop.
As far as pigtails and adapters that were needed; since I used a Mac Mini I required a Mini-Display Port to VGA adapter (
http://www.amazon.com/Apple-DisplayP...2576056&sr=8-3) and a Mini-DVI to VGA adapter (
http://www.amazon.com/Apple-Mini-dvi...6094&sr =1-3). These would only be required if you're also using a Mini.
I also needed 2 bare-wire to mini-rca (headphone jack) cables. The bare wire ends splice to the GM 2005 harness connector (front and rear channel) while the mini-rca end plugs into the audio out. Since the Mini only has stereo out I also used a mini-rca Y-adapter so the audio went to both the front and rear channels. If you used a PC with a surround sound audio card you would have multiple channel audio outputs on the board, so you could simply connect the front channel to the front and rear to the rear and end up with quadraphonic stereo.
I also ordered a right-angled OBD-II extension cable (
http://www.scantool.net/accessories/...1962f-2ft.html) as the standard cable came straight out of the plug when connected and interfered with my leg room.
Other than that, you simply need an assortment of varied lengths and types of USB cables to accommodate the devices that you're connected and the locations where you are installing them. I'm fairly anal about cable neatness and length so I tend to have to order my cables online to get exactly want I want. This is a good source:
http://www.cablestogo.com/
The radio unit that I have works as well as the stock headunit did. I'm actually looking at a replacement USB radio device though. My current unit, the Visteon HDZ300, is a bit bulky and I wanted a smaller device with a built-in antenna that I can mount in the passenger-side pillar.
Here's some other online resources that may be helpful:
Logic Supply:
http://www.logicsupply.com/
Many different industrial/automotive computer systems...in case you're not a fan of Apple, or feel more comfortable with a straight-up, bare bones PC.
Car TFT:
http://www.cartft.com/
More carpc stuff, but they also carry an 8" 16:9 open-frame touchscreen that has worked well for me in the past (CTF800-WMSL). The Revosys units that I currently have are apparently getting hard to find.