Applications, Control Panel features, documents, email and other files are all searchable from the Start menu, with results appearing as you type.
The indexing has no noticeable impact on system performance and results are accurate. The results provide more than a simple text match; type "disk space", for example, and the option to defragment your hard drive appears, although neither of the search terms appears in the feature's title.
Based on this search advantage, Windows 7, at last, feels like an OS that wants to work with, rather than against, you; an OS where the front-end has been designed with care, rather than carried over from the previous version.
Windows 7 is, in terms of usability at least, the front-end that Vista has long deserved.
Also in the Best Windows7 Features series:
Part 1: Ease of Use, snapping Windows
Part 2: Networking made easy
Part 3: Device management for your PC