Vista - Download Problems - the files will not run!

Hello! Firstly Thank You for this great community for Vista troubleshooting

Problem...
A lot of the time when I download a file from the internet it won't run or install afterwards. There are a couple of different problems I've come across:

Windows Update: Some of the updates have successfully installed. Some fail to install every time.. I have 3 updates sat waiting to be installed but they fail when I try.

NForce Motherboard Driver: I downloaded the file from official website. Run the install program and half way through it errors: "The contents of this file cannot be unpacked. The executable you are attempting to run has been corrupted..."

I tried to download this file approx. 5 times. It makes sense that this error is because or a bad file, but I successfully installed the drivers by: Download the same file, from an XP machine, copy it over and install. I have this error alot, on different files not just the driver installer.

ITunes: Downloaded the Vista x64 version of this from Apple.com. When I run the installer (and as Administrator) I get prompted for the Admin Rights bit, click Allow and the application disappears and nothing else happens.

YouTube: As something I think's worth pointing out, if I stream a video on YouTube there's a good chance internet explorer will crash half way through the video.

My Spec...
OS: Vista Home Basic 64 bit
CPU: Intel C2D E8200 @ 2.66GHz
Mobo: GeForce 7100/NForce 630i Motherboard (by EVGA)
Network: Wired, Built into Motherboard
RAM: 4Gb DDR2 Cheap Stuff Corsair Value I think
GFX: GeForce 8500GT

Thanks for reading and I hope someone can help me!

(I'm pretty comfortable with computers, but Vista is brand new to me, so I apologize if I've missed out any necessary information but I should be able to get it for you if you can suggest something!)

Hi there,

Have you tried saving the file first to your desktop and then tried running the program? You are administrator of your computer? You have tried to run the file as administrator? Have you tried downloading from another internet site?

If that fails you can log in as the true administrator of the computer (vista disables by default) see that works :O)

Scratch that last statement - if this is a problem with your profile running as the full admin account only makes you more vulnerable than you were in XP.

iTunes and Vista x64 don't play nice. That is one problem. The second is that it depends upon which nForce mobo drivers you are using, but don't install nTune - that has whacked me every time I have installed it on this box, and it is barely 3 months old.

Finally, you an simply go to the Microsoft download site and look up the KB number of the three missing updates and download them and manually install them....

Are you running a third party software firewall? Are you using any download managers to download your files?