This is a good list of windows system optimization tools that are free.  If you have to support macs for a non-profit or for people with limited means this will do many of the things commercial software might do more conveniently.

Digeus System Optimizer is the smartest way to solve computer problems and protect your valuable data. This software is real easy to use and helps you eliminate system crashes, resolve computer problems, and restores your system to healthy state. Main Function : – Eliminates system crashes, freezes and slowdowns – Automatically identifies and repairs common Windows problems – Easy to download, install and use – Free support and services Minimum s … Read More

via Jovan’s Blog