1) Check you available disk space - For now the best information available is as follows:
Free drive space required: Stand-alone installation (DVD .ISO or SP1 Download) X86-based: 4.1 GB X64-based: 7.4 GB
Installing SP1 using Windows Update:X86-based: 750 MB X64-based: 1050 MB
Note: I would be more inclined to use the following values when using Windows update:32-Bit / X86-based: 1.5 GB, 64-Bit / X64-based: 2.6 GB
2) Run Disk Cleanup. Start/All programs/Accessories/System Tools/Disk Cleanup. Place check marks in at least the following options: Temporary Internet Files, Recycle Bin, Temporary files
3) Create a new System Restore point just prior to installing SP1. Click ‘Start’ and enter:Create a system restore Select ‘Create a restore point’ at the top of list of options and from the ‘System Properties’ Window click on the ‘Create’ button located in the lower right corner. Enter a description (Example: Prior to installing SP1) and click ‘Create’. Click ‘Close’ after the restore point is created and ‘OK’.
4) If at all possible create an Image Backup of the Windows drive or partition. This backup can be your ticket back to a fully functional version of Windows should you encounter problems when installing Service Pack 1.
5) Install the Windows 7 device drivers for your make and model: Go to the manufactures support web site and download the Windows 7 drivers to a folder on your PC and then start by installing the chipset/motherboard drivers, followed by the USB, SATA, LAN, Audio and all remaining drivers.
Most AV software will have a menu / settings option to disable real time or active scanning. Don’t forget to enable active scanning after installing SP1.
8) Run the SFC/SCANNOWcommand: This will check and repair if necessary any critical Windows system files prior to installing SP1. Click on Start/All programs/Accessories then Right click on Command Prompt option and select 'Run as administrator'. At the command prompt enter:SFC/SCANNOW
9) Run the System Update Readiness Tool: http://support.microsoft.com/kb/947821/en-us Microsoft released the System Update Readiness Tool to resolve certain conditions that could cause installing updates and other software not to work. You do not have to manually run this tool. This tool is offered automatically through Windows Update to computers that have a condition that the tool could resolve.
10) Rename the 'Software Distribution folder': a) Click the Start Button, click 'All programs, and click on 'Accessories'.
b) Next Right click on the 'Command Prompt' option and then click 'Run as administrator'.
c) In the 'Command Prompt' window enter: net stop Wuauserv and press the 'Enter' key.
d) Next click the Start/Orb button in the taskbar, in the 'Search' box, enter: %windir% and press the 'Enter' key.
e) In Windows Explore view, search for and locate the folder named "SoftwareDistribution".
f) Right click on the folder and select the 'Rename' option and change the name to: SoftwareDistributionOld
g) Close Windows Explorer and in Command Prompt window enter: net start Wuauserv and press the 'Enter' key.
h) Wait for the "Windows Update Service has successfully" before exiting/closing the command prompt window.
i) If you open Windows Explorer you should see that new "SoftwareDistribution" folder has been created.