Take a moment to look at the Mercury KB - search on Vista and you will find a host of information (in one article). Items such as running QTP as administrator (perhaps why nothing happens!). Changes are also required in IE7.
...And the .Net addin 9.2 does work with Vista - or I haven't found any problems so far.
If you had to identify, in one word, the reason
why the human race has not achieved, and never
will achieve, its full potential that word would be "meetings".