I am unable to download itunes on my computer...i get the following error message...

An error occurred during the installation of assembly ‘microsoft. VC80.CRT, version= “8.050727.4053”, type=”win32”,publickeyToken= “1fc8b3b9a1e18e3b”,process or Architecture=”x86”. Please refer to Help ans Support for more information. HRESULT: 0x800736B3.

how can i fix it so that i am unable to download itunes on my vista laptop?

thanks