Windows 7 and Windows Server 2008 R2 Service Pack 1 (KB976932)
Windows 7 and Windows Server 2008 R2 SP1 helps keep your PCs and servers on the latest support level. It also provides ongoing improvements to the Windows Operating System (OS), by including previous updates delivered over Windows Update as well as continuing incremental updates to the Windows 7 and Windows Server 2008 R2 platforms based on customer and partner feedback. This enables organizations to deploy a single set of updates.
Size: 262.7 MB - 1953.3 MB

Windows 7 Upgrade Advisor
To see if your PC is ready for Windows 7, download the free Windows 7 Upgrade Advisor. It scans your PC for potential issues with your hardware, devices, and installed programs, and recommends what to do before you upgrade.

Remoteserver-Verwaltungstools for Windows 7
Remote Server Administration Tools (RSAT) for Windows® 7 enables IT administrators to manage roles and features that are installed on computers that are running Windows Server® 2008 R2, Windows Server® 2008, or Windows Server® 2003, from a remote computer that is running Windows 7.
Size: 215.1 MB - 437.2 MB

Windows XP Mode
Windows XP Mode for Windows 7 makes it easy run many of your productivity programs that run on Windows XP on Windows 7. It uses virtualization technology such as Windows Virtual PC to provide a Virtual Windows XP environment for Windows 7.
Installation instructions and Release Notes for Windows Virtual PC and Windows XP Mode
Alternate Download
Size: 444.9 MB - 909.0 MB