Since I develop for both Windows and Linux, I running Windows Vista as my host system with VirtualBox virtualization software. I am currently using Ubuntu 8.04 LTS installed as a guest system for Linux development. One thing to remember (which I always tend to forget), whenever you upgrade VirtualBox or the Linux kernel, you need to reinstall the VirtualBox Guest Additions, otherwise woe is you! It’s kind of a hassle, but it keeps Ubuntu happy.