I uses Microsoft Wireless Laser Desktop 4000 but the CD that comes with it display known compatibility issue warning.
Microsoft has released latest version of the drivers & software that is compatible with Windows 7 and available for download at
The keyboard software (IntelliType Pro) and mouse software (IntelliPoint) are available for the 32-bit and 64-bit editions of Windows® 7. Please use the drop-down lists below to get the appropriate download.
Direct links to Microsoft Mouse and Keyboard Hardware - Download Software
BTW Microsoft claiming that their hardware are Windows 7 ready. You can find compatibility details at http://www.microsoft.com/hardware/windows7/support.mspx