Our school accounts are usually limited to about 80MB of disk space, perhaps up to 500MB for those taking art, graphics or technology. The majority of the PCs have 128MB of RAM, with a few going up to a whopping 512MB. Executables of any kind will not run. On a good note, however, there has never been a virus on the school system (conficked flash pens, for example, just wouldn't open as easily).
The only exception to any of these is a solitary computer for electronics students in the physics lab, which has 1GB of RAM and a large hard disk in order to run the CAD software properly. It also doesn't block executables, and as such was at one point infested with all manner of vile creations.