I can't download iTunes onto my laptop?

I got an iPhone 4s forrm birthday which was yesterday, and I wanted to put music on it. So I tried the drag and drop method by connecting the phone to my laptop and dragging all my downloaded music to it, but it didn't work. So I researched and found out that I need iTunes on my computer to do it, but I tried to download it and it didn't work. This is what happened:

I clicked run, and it came up with the 'Welcome to iTunes' window. Then I clicked next and then instal, and the installing window was on my screen for literally 2 seconds, and then it came up with this message:
The installer encountered some errors before iTunes could be configured.
Errors occurred during installation. Your system has not been modified.
Please run the installer again, or click Finish to exit.

So I tried it about 3 more times and it keeps doing the exact same thing. Now unless there's any other way to put music on my iPhone without using iTunes at all, I really need help with this.

Download it from iTunes.com connect your phone to the computer with the cable put the Musics you want and then you'll find it on the music app in your phone

Never happened with me, this might help though, and happy birthday. :
http://answers.microsoft.com/...beb0095cb6

Completely uninstall iTunes from Control Panel and try again. If it fails again then try finding an offline iTunes installer. (Google.)