There are different methods to get Windows 7 SP1 on the Internet. You can either buy or rent the software, which is very expensive. I do not recommend this because it will only make you have a very slow computer and it can cause a lot of headaches. You can choose to download it for free and that can be done from many different places. You can find sites on the Internet that provide downloads of Microsoft's software and that includes the Windows operating system.
The other option is to use third party programs that are available that are able to update the software and get new versions of the applications. This can save you a lot of money if you are looking to purchase the latest version of the application. When you download the software, you will just need to point and click so the software will install and run on your computer. The application is able to run in a virtual machine and run inside your desktop.
There are many ways to get the software for free. I recommend you to look for the latest Windows updates on the Internet. You can find them through a software like Nirsoft's OCTGN. They have over thirty different tools that allow you to update the applications. It is a better way to get the newest versions of the applications because it is going to be updated constantly and that is going to keep you up to date with the latest version.