System Sweeper is an important tool that Microsoft apparently uses to scan computers that are manifesting problems that are otherwise not identifiable. I gather that people calling Microsoft for help and still have weird problems will be directed to this free utility. It's a shame that more people don't know about this utility because it finds viruses, trojans, and even root kits.
One of the problems with antivirus software is that once a bad piece of software gets on a computer, it can hide from the av software. This is especially true of root kits -- which dig under the operating system. The only way to find such deeply buried malware is to scan the computer's hard drive before it has been booted. That means booting from another device. System Sweeper comes from Microsoft as a bootable system. The image file one downloads is burned to a CD-ROM. The CD-ROM boots into a specialized version of Windows that has as its own function the running of System Sweeper. So far, most of the people I have given this disk to have come back reporting at least minor problems that they previously did not know about.
I suspect the main reason Microsoft does not make this important tool well known is because most users don't understand the idea of downloading ISO images and how to boot the CD-ROM drive. Because problems on your users' systems will come to haunt your network, it makes sense to make disks for your users and help them run this utility on their home computers.