Worlds on Vista
Worlds will not install the stock worlds if you have UAC enabled in windows vista
this page describes the easiest way to turn it off

first go to control panel and change to classic view then open administrative tools

next run System Configuration

select the tools tab then click Disable UAC and click the launch button ..note you may have to restart at this point
Finally go back into worlds and get all the stock worlds (use jimblys gauntlet)
after this is done you may re-enable UAC