On February 22, 2011, Service Pack 1 for Windows 7 was made available for downlaod ffrom the Microsoft Service Pack Center. Windows 7 SP1 includes previously released security, performance, and stability updates, plus some improvements to features and services.
Microsoft suggests you just let the normal Windows update system handle installation of the service pack but yoiu can can download the file and install it manually. The install will take around 30 minutes and you will have to reboot the PC during the process.
You will need from 750MB to 7400MB of available disk space storage to complete the installation procedure, so plan accordingly. If you have a pre-release version of SP1 installed, you will have to uninstall it before you install the latest version.
Some antivirus software may prevent SP1 from being installed properly, so you may want to temporarily turn off your antivirus while the installation takes place.