Every time I install a game, or even OpenOffice, part of the installation routine is installing yet another Visual C++ 2005/2008 redistributable, right next to the 10 others I already have on my system.
Visual C++ redistributables are components shipped by app developers who use Visual C++ to write their software. By using Microsoft's well-tested and widely used code inside their apps, developers save their development cost by avoid writing commonly-used code (e.g. sin and cos math functions and handling of common user interface elements like textbox or button). Due to fragmentation in the runtime versions used by the app developers, you would see a long list of Visual C++ redistributables if you install a lot of apps. Uninstalling one Visual C++ redistributable could save you a few megabytes of disk space, but you risk breaking some apps in doing so.
Microsoft also has to support a lot of Visual C++ runtimes because it has no idea which one the app developer would choose. Multiple versions of Visual C++ redistributables can be required even within the same app, for example, if an app depending on Visual C++ 2008 redistributable uses a component depending on Visual C++ 2005 redistributable, the app's developer must ship both versions of Visual C++ redistributables. On a 64 bit computer, the system could have both x86 and x64 editions of Visual C++ Redistributables installed, since Visual C++ redistributable is a commonly used component, and it is normal to have both 32bit apps and 64 bit apps (or even apps that contains both 32 bit code and 64 bit code) installed on a 64 bit system.
Download the 64-bit Visual C++ 2005 SP1 redistributable runtime modules from Microsoft. At the time of this writing (April 2008), the package to download is identified as "Microsoft Visual C++ 2005 SP1 Redistributable Package (x64)" and is available from the following link: =eb4ebe2d-33c0-4a47-9dd4-b9a6d7bd44da&DisplayLang=en 2b1af7f3a8