As we previously reported Windows 7 SP1 and Windows Server 2008 R2 SP1 become generally available for download today. Microsoft had previously made SP1 available to MSDN and TechNet users (as well as Volume License customers) on February 16th.
SP1 is available from the Microsoft Download Center or via Windows Update. If you are updating a single PC the best approach is to use Windows Update. If you are deploying it across multiple machines it is best to download the standalone installer to save bandwidth.
As a general tip, it is worth backing up your important files and data before installing SP1, however there is no known reason to think that there will be any trouble with the installation. It is also worth checking that your malware software is up to date. Laptop users should make sure that there laptop is connected to the mains electricity to avoid the laptop shutting down, due to a depleted battery, during the update.
After installing SP1 you will need to reboot your PC. Once it restarts you can reclaim some disk space by removing the service pack installation specific files. Run Disk Cleanup and click on the “Clean up system files” button then check “Service Pack Backup Files”.