From Wide Angle Software:
Apps to PC is a Windows utility which allows users to transfer any apps or app documents that they have downloaded onto their iPhone, iPad or iPod Touch directly to iTunes. Apps to PC is incredibly useful when it comes to re-installing Windows on your current machine or if you are changing your PC for a newer model. The problem is that a new installation of iTunes will not contain any of the apps that have been downloaded in the past and this process may even result in apps being deleted from the user's iOS during the switch over.
This is where the Apps to PC program steps in. With this product, the user has the freedom to select which apps they would like to copy to iTunes and which they would like to disregard. This is much more beneficial for users than the iTunes method of transferring all of the purchases over. Sometimes we might download an app thinking it's really useful only to be disappointed, therefore you won't want to transfer it over to your new machine. With Apps to PC, you can pick and choose your favorite apps and get rid of the others that you don't use.
Another benefit of the Apps to PC program is speed. Using this program is a lot quicker than re-downloading all your favorite apps from iTunes and why should you have to? You've already downloaded them once; it doesn't make sense that you should have to repeat this process again! Even if a user has a slow internet connection or are unable to get online, they can use the Apps to PC program to recover all the apps from their iPhone in just a few minutes and with a few simple clicks of a mouse.
As well as keeping all of your favorite apps safe when transferring information between your iPhone and your PC, the Apps to PC also allows you to navigate around individual apps file systems. This enables a user to copy files to and from apps file space which is really convenient and simple to do.