I am unable to complete the installation my iTunes software.

Itunes for Windows:

http://discussions.apple.com/category.jspa?categoryID=150

There is also a separate forum for iPhone.

Step 1. Go to the Apple Download site and enter your email address. Choose the Windows version of the software and click on "Download iTunes."
Step 2. When the "File Download" box appears, click on "Save" and watch as it downloads to your PC.
Step 3. After the installation is done, look for the iTunes Setup file on your PC desktop and double click the icon.
Step 4. Follow the installation instructions and select options that suit your needs. You can select the icon to appear on your desktop or even select iTunes as your default music player.
Step 5. Click "Next" to install the program on to your computer. After installation, you will need to restart your computer.
Step 6. Open your newly installed iTunes program by clicking on the iTunes icon.
Step 7. The program will search for the MP3's that are already on your computer. Allow the program to search for MP3's by selecting "Add MP3s and ACC Files."
Step 8. Decide if you want to have iTunes organize your files. If you want to keep them as they are, click the "Next" button.
Step 9. iTunes will open and you can browse and play your music files.

Everything is fine until Step 3. iTunes comes up with an error message and will not complete the installation. Error 7.

I'm suffering from the same problem and am desperate!