First Some common sense rules for computer usage in the classroom. Software upgrades come out every two years. Software upgrades doubles in size every 2 years.
Software upgrades run twice as slow as past releases.
The software grows with the hardware. This means that the drop in memory and storage cost is always coupled with increases in software memory requirements. The number of know errors in software is a function of the ability of users to find them. The ATP should be centered around your classroom expected usage, the number of students, and the actual software to be used. Most vendor supplied diagnostic testing is designed around minimal usage.