DotNet and VC++

I cannot install .NET 3.51 sp1 on Windows Vista Home Premium (32bit). When I
try to I get the dependancy message indicating .Net 3.0 is not installed. I
checked the Control Panel and tried Turning it off, rebooting and turning it
on again.

Yet, .NET 3.51 still says it's not installed.

Also, I cannot install the VC++ 2005 or 2008 redistributable library. All
kinds of problems, sometimes I get the message that Setup has stopped, other
times I get an error message saying the installer quite unexpectedly and
cannot continue (or something similar - too many messaged to try to be
diligent and I guess I can start over and record each one if need be).

I've checked every page on every blog on every site I can find that even
remotely discuses these problems.

I need to have the installed but am now at a loss as to what I can do to
install them.

I began having this problem when I noticed that the Windows Update.NET 3.51
SP1 failed. I created a new account (admin rights) tried that no go. I've
gone to Windows Catalog and downloaded the X86 files and I need to run
setup.exe, there is none.

Can someone please help?

Thanks.