[GTALUG] simple straightforward tool for mainaining small networked of imaged linux boxes

Hi, Over at Free Geek Toronto <http://www.freegeektoronto.org/>, we have a small computer classroom of desktop boxes that run Linux Mint. Every couple of weeks we re-install clean images by hand. The process is pretty labourious and time-consuming, and we would much rather automate it somehow. However, none of us is a real sysadmin, and the tools I know a tiny bit about (landscape, puppet) are non-free and relatively complex. We have very limited financial resources and our volunteer capacity is also a bit strained right now. Does anyone have suggestions for a simple, easy way to automate the flashing of images in a small network? Thanks as always -- this is my first post on the new list! Matt