In an X environment, a host is a system that provides resources for an X Server. In a diskless workstation environment, the services provided by a host system will generally include session authentication using xauth and xhost, session management using xdm, file transfer services such as nfs and tftp which provide system fonts and a bootable image to be loaded into the X Terminal's RAM, and windowed client applications (e.g., Mozilla, Open Office).
Our environment consists of 25 diskless workstations with 15 workstations using Mozilla, 6 worsktations utilizing a proprietary graphical application written in Java, and 4 workstations with an application running under a terminal emulator.The 6 java-based workstations use Gnome as their desktop environment. The remaining 19 workstations use FVWM2. To support that environment, we use 2 dual processor pentium 3's. One system has 1 gig of ram, the other has 500 megs. We have found that the stations running Gnome and Java use dramatically more memory and cpu than the stations running Mozilla.
In order to use Linux as a host for a network of thin client workstations, you will want to get the latest release of the the XFree86 X Windows System, FVWM2, and nfs-utils. Assuming that you are using an RPM-based distribution, you will want the following packages: Xfree86-font-utils, Xfree86-libs, Xfree86-devel, Xfree86, Xfree86-truetype-font, Xfree86-xdm, Xfree86-base-fonts, nfs-utils, fvwm2, fvwm2-icons. To verify installed packages on an rpm-based distribution such as Redhat, you can use "rpm-qa | grep (packagename)". To install or update those packages simply download them from their maintainer or from your installation media with and "rpm -Uvh (packagename)". Alternately, you can use a graphical front end to rpm such as gnoRPM to maintain the required packages are installed on your system. For debian-based systems, or for Gentoo, please consult your system documentation on apt-get and portage, respectively.