iTALC is cross-platform and easy to install. There are binary packages and installation instructions available for several Linux distributions, including Debian, Ubuntu, SUSE, and Gentoo. You can also download the source package. I set up iTALC in Fedora from source without any issues and managed clients running other Linux distributions and Windows XP.
iTALC’s hardware requirements are modest. Its developer recommends 512MB RAM and 1GHz processor and a graphics card (the current breed of on-board graphics would do) on the master (teacher) computer. You’ll also have to install iTALC on all students computer as well. When installing iTALC on the student’s computer, select only the “iTALC Client Application (ICA)” option. To add a computer you’ll need to know its IP address and MAC address. The procedure is explained with screenshots on iTALC’s wiki.