It depends upon your server, how many clients, etc. Some FOSS (Free, Open Source Software) examples are:
The best (only!) way to survive administering a school district is to convert every desktop machine to a disk-less client.
A complete multi-platform internet cafe management suite.
Internet cafe' w/ disk-less machines
Free, easy to install VM Ware (Virtual Machine) that provides a PXE-server image and everything else you need in terms of software for driving a pool of internet cafe machines. The package use Gentoo Linux as the operating system.