On the quicktime download page apple has a survey for vista users to fill out if you run into problems. (Basically a bug report form)
There are some known issues with Quicktime versions Prior to 7.1 and vista so make sure you are running 7.1.0 or higher (latest is 7.1.3)
thanks kyle for the info…i’m running 7.1.3
but not vista yet!!! 8) ???