I'd start by ruling things out, which you have already partly addressed.
My first question therefore would be: Is your hardware all working now?
The best, easiest way to test this out is to run an operating system on it. Obviously you are trying to do this with Vista, but there are alternatives such as XP, or even easier would be something like Ubuntu, which you dont even need to write onto your hard drive but can just run from a LiveCD.
This will give you the opportunity to have a fully working system that you can mess around with and test out. Once you've confirmed that all your physical bits and pieces are working, you can move on from there.
http://www.ubuntu.com/getubuntu/download