Timely topic.
I was one of the pioneers of the carputer / dashpc movement back in 1999. You can see my Jetta here:
http://dashpc.com
Here's a picture of my first interface (Perl / TK):
I was one of the developers of FreeDiag for a while on Sourceforge, and I'm the host of the Linux based Dashpc code (it's linked to from my site, or search Sourceforge).
I haven't been active on it for a few years, but maybe I can offer some advice about some of the hurdles I had to overcome doing my installation.
Unfortunately, my Aspire doesn't have ODBII, but my new Insight does.
I just wish I didn't have so many projects on my plate at the same time!