Whether working with the keyboard alone is much efficient than using a mouse is debatable, there are applications such as Launchy that push the debate in favor of working solo with the keyboard. Launchy is similar to Mac OS X's  Spotlight, and more configurable than the search feature within the Windows Start button.

As you can see, the level of customization is deep. I think the most powerful feature is you can have different folders be searched for a specific type of file. For example, in most people's case, a great amount of different files get placed in the Documents folder, when only the ones that are accessed are Microsoft Word files! So instead of spending 20 seconds looking for a specific file, simply configure Launchy to your taste!

In the MS Word case, add the Documents directory and specify that only Word documents should be indexed. To do this, you would simply type in "*.docx" without the quotations where "docx" is the Word file type. In my case, I work with programming files, word files, pdf, etc. The variety is considerable, so I just have Launchy search and index all the various files but only within that folder. Placing such a simple restriction has a huge influence on how efficient Launchy will be at finding the desired file. By default, Launchy will index your applications, but you can always take it a step further! Questions, comments are always welcomed.