Instructions from Microsoft on updating your Remote Desktop client
For Windows x64 (64-bit): Download 64-bit Installer
For Windows x86 (32-bit): Download 32-bit Installer
For Windows x64 (64-bit): Download 64-bit Installer
For Windows x86 (32-bit): Download 32-bit Installer
For Windows 7 x64 (64-bit): Download 64-bit Hotfix
For Windows 7 x86 (32-bit): Download 32-bit Hotfix