My wife takes Operating Systems this semester. The course is quite big (they combined 2 courses into one) - having a theoretical part (by Silbershatz. et al book) and a practical part.

The practical part is playing with Linux's source code, modifying and recompiling its kernel. How cool is that !

The students were guided to install VMWare and RH 8 on top of it with the 2.4 kernel. During the semester, in order to learn the practical aspects of operating systems, they will do various modifications to the kernel, recompile it and see the changes in action. For instance, the first warm-up homework is modifying the source of execv(3) to print the student's ID before running each process ! Oreilly's "Understanding the Linux Kernel" is one of the course books.

VMWare's part in it is clear. Modifying the kernel is dangerous, and VMWare is a convenient sandbox to do that. Screwed the OS up ? No probs, just replace the image with a fresh one.

We installed VMWare (with Linux on it) at home and it's very cool - even to just practice with Linux. It's easy to set up shared drives between the host (Win XP) and the virtual Linux OS, make the virtual OS use the PC's resources like ADSL, CD/DVD drives, etc. It's a good step in a transition-to-Linux.