VMware allows you to run 'virtual machines' inside a Linux host. It is not an emulator. It provides a virtual computer within the host which can boot whichever OS you decide to put on the filesystem image that is used as a harddrive. It will run DOS 6.22, Win 3.1, Win9x, WinNT/2000/XP/2003, Linux, Novell, and more. The only main requirement is a 400 MHz or better machine, along with lots of RAM (128M minimum, 256M recommended).
JExpress is a Java installer builder and auto-updater. It gives you your choice of a standalone installer, including both native and cross platform installers and updaters for Windows, Mac OS X, Linux, and Solaris, or a Java Web Start one-click install. You create your installer quickly with your choice of a simple wizard or a powerful advanced interface, both included. You can bundle the exact JVM you want with your installer. The auto-updater gives you a continuous revenue stream after the sale. Your software is always up-to-date, so your customers have fewer problems. You also get all the features you expect in a top end installer. Your Java application becomes a native program just like any other. On Windows it's an EXE, on Mac OS X an app bundle, etc. If you need something really special, you can customize your installer by adding simple Java classes. You can even get a source license at a reasonable price.
Tenable Nessus is a world-leader in active vulnerability scanners. It features high-speed discovery, configuration auditing, asset profiling, sensitive data discovery, and vulnerability analysis of your security posture. Nessus scanners may be distributed throughout an entire enterprise, inside DMZs, and across physically separate networks. It is free of charge for personal use in a non-enterprise environment.