It's a bit of a mystery to me why the client/server network architecture persists so insistently. Monitoring and administering herds of individual PCs, even with good remote administration tools, is way too much unnecessary work. The majority of users would be served perfectly well by a server/thin-client structure, and network administrators would have a much easier time of it.
In such an environment, everything lives on the server and is controlled by the server administrator: applications, data storage and user accounts. Security is simplified. Backups, customizations and updates are as easy as falling off of a log. Users can log in from anywhere without hassles. Organizations can save a lot of money by keeping old PCs in service that are marginal as stand-alone systems. They can save even more money by not needing to keep hard or removable drives of any kind in the client systems.
Some of those savings can be put into a first-class server made of real server parts, and we don't mean wimpy PC parts. Redundant hot-swap power, redundant hot-swap disks, a real serial console, server-quality motherboard and network cards if you have not experienced using first-class hardware, you're missing out. A whole host of troubles evaporate with good hardware.
The Unix/Linux world excels at terminal services. To get your feet wet in the terminal server world, give Edubuntu a try. Edubuntu is based on Ubuntu, which is derived from the excellent Debian Linux. Although it is targeted at classrooms and comes with a lot of software you probably will not need, it works just fine in the enterprise. It's an excellent terminal server that is exceptionally easy to install and set up. Fine-tuning the package selection is very easy. You're not limited to what comes on the installation CD but have access to both the Edubuntu and the vast Debian package archives.
Edubuntu is both free of charge and Free Software, licensed under the GPL. If you're already experienced with Debian Linux, the Getting Started With Edubuntu page may be all you need to get going. Visit Edubuntu.org/ for downloads and information.