[est1895]

Is it safe to install: Microsoft .NET 3.5 Service Pack 1
                            Microsoft Visual C++ 2005 Redistributable Package (x86)
                            Microsoft Visual C++ 2005 Redistributable Package (x64)
                            Microsoft Visual C++ 2005 SP1 RP ATL Security Update

My OS is Windows XP 32bit home.

[S-99]

As long as your running xp sp3, you should be fine. Except, you won't be installing microsoft visual c++ 2005 redistributable package (x64).

[est1895]

So I would install this and not the (X64): Microsoft Visual C++ 2005 Redistributable Package (x86)

I would also like to know what these do to the system?

[The E]

The .NET service pack fixes a few things in the .NET runtime, which is a service needed by several Windows components and third-party programs.

The Visual C redistributables contain code needed by programs written using Visual Studio, specifically programs written in C and C++. They are libraries that contain several important low-level functions.

The last thing mentioned is a bugfix for these redistributables.

You will not (or rather, probably not) see any impacts from installing these, negative or positive. However, given that the bugfixes close security holes, not installing them would be stupid.

[S-99]

Microsoft Visual C++ 2005 Redistributable Package (x86)

Yes you would want to install that one. The x64 version wont be installable since your operating system is 32 bit.