Your best bet is to start the install and then walk away for a while. The installation time isn’t terribly long, about 30 minutes, but depending on your internet connection, it’ll take quite a while to download. If you have Windows Update set to automatic, the service pack will not make you more secure. If you haven’t installed anything off Windows Update in a while, first, shame on you! It’s important to keep yourself updated! Also, this release is essentially a big fat roundup of all the security fixes and bugfixes since Windows 7 was released, combined with a few extra bits of functionality. It’s an optional update (at this point) in Windows Update, so you’ll only get it if you choose to install it.

It’s in Windows Update? Will I Get it Automatically?.

Where Do You Download It? While you can download the service pack manually from the Microsoft Download site, you should probably just go through Windows Update and select the optional SP1 update from there, since it’ll only download exactly what you need.

Whether you were going to ask these questions or not, we’re giving you the answers that you really need to know. Answers to Questions You Should Be Asking

Win7 servicepack 1