Vista as in Windows Vista, instead of XP - Powerstrip has issues with it.
Hmmm, if the Advanced Timing button is not greyed out, it means powerstrip supports your card and believes it can program it.
The custom resolutions thing - could be something ATI have changed in cat 7.1 but I doubt it.
Might be worth posting your pstrip.ini file in the Entech Powerstrip forums....