To boot the recovery partition on a Vista Dell XPS laptop, you need to press F8 as the laptop boots.

This will bring up the Vista boot menu, from which you can choose Recovery Console (usually the top option). Vista will then boot into a special mode, not unlike Safe Mode, and after logging in, will give you the option to run the Dell Recovery Tool. The recovery process is actually very fast – about 10 minutes in my case.

Unfortunately, this took me ages to find. Usually, laptops tell you how you can run a System Recovery when they boot, e.g. “Press F10 to run Recovery”, but the Dell XPS Vista laptops don’t do this at all. It certainly left me bewildered, until I stumbled upon the solution, via a Google search.