So you did a full clean reinstall of Windows 7? Clean as in a reformat? You are absolutely sure that SP1 is not on there anywhere?
Just to be sure give this a read.
Next, try making sure all Windows 7 updates prior to SP1 are installed. Visit Windows Update until no updates are shown.
Next, you can give this a try:
Downloading and installing SP1 from the Microsoft Download CenterThe manual download can be found here.
If you have problems getting the service pack from Windows Update, you can download the SP1 installation package from the Microsoft Download Center, and then install SP1 manually.
Go to the Windows 7 Service Pack 1 download webpage on the Microsoft website, and then click Continue.
Choose either the 32-bit (x86) or the 64-bit (x64) version of SP1 depending on whether you're running the 32-bit or the 64-bit version of Windows 7, and then click Download.
To find out which version you're running, click the Start button Picture of the Start button, right-click Computer, and then click Properties. Under System, next to System type, you can view the operating system.
To install SP1 immediately, click Open or Run, and then follow the instructions on your screen. To install SP1 later, click Save and download the installation file to your computer. When you're ready to install SP1, double-click the file.
On the Install Windows 7 Service Pack 1 page, click Next.
Follow the instructions on your screen. Your computer might restart during the installation.
After installation is complete, log on to your computer at the Windows logon prompt. You might see a notification indicating whether the update was successful.
If you disabled your antivirus software, enable it again.