For a long time, some Microsoft officials have privately griped that PC makers don't present Windows in its best light. They clutter desktops with icons that are often little more than ads for third-party products; include confusing utilities that duplicate functions already in Windows; require lengthy setup; and configure PCs in ways that slow them down.

One consequence, in the eyes of these Microsoft executives, is to confer an advantage on the company's main operating-system rival, Apple .

Now, Microsoft is doing something about the situation. In a program unknown to most computer users, the company has been using its small chain of retail stores and its online computer store to sell customized versions of popular PC models that have been streamlined for a cleaner look and better performance. It calls these machines "Signature" PCs. They retain the maker's brand, but sport a special Signature desktop and configuration. And they cost about the same as the identical stock version of the machine sold elsewhere.

Microsoft also offers a program that, for $99, will turn users' Windows 7 PCs into Signature versions, if the owner brings the computer into one of its 16 stores, due to grow to 21 outlets in coming months. All Signature computers come with 90 days of free phone support, as well as help at the stores' "Answer Desks," which are like the Genius Bars at Apple stores.

I've been testing three Signature models and comparing them with the same machines as sold elsewhere without the Signature modifications. I found the Signature versions much cleaner and easier to navigate and faster in a variety of tests.