The idea of virtual machines isn't new. Its been heating up a good bit this year however. There are open source VM products now for Linux and both Microsoft and VMWARE have made parts of their products available for free. I'm going to talk here about my favorite one.

VMWARE -- now owned by EMC -- makes what to me is the best virtualization product line out there. I used to swear by their Workstation product and had been using a version 4.5x for some time. I hadn't upgraded to version 5 because I had no need and it cost money. Now, they have a full line of products and it can be hard to figure out which you need. Here's help:

VMWARE Workstation -- This is a high end tool for running virtual machines on your PC. What makes it special is that you can take multiple "snapshots" (sort of frozen in time backups) of the VMs and revert back to them as needed. You can also freeze VM's and look at memory utilization and driver states. If you're writing high end software, its great. Its also not free.

VMWARE Server -- (FREE, currently in BETA, very stable) This is everything the workstation product was in version 4.5, plus a lot more. Essentially, you define virtual hardware and boot an imaginary new computer. You load the operating system you want on it and inside, it never knows its not a real computer. You can run several at once, subject to memory and so on. I often run a linux server inside my windows workstation but am seriously considering switching to running a windows workstation inside my linux server instead. What's more, now you can set VM's to start and run automatically when the machine is started without having to log on, and to run under a specific userid or even administrator. This literally lets turn one back room server into several for all intents and purposes. You even get a client side software that can connect to the host machine running your vm's and view them as if they were running locally. VERY cool.
--> TIP: During the beta, turn off the debugging which slows things down by using debug = "FALSE" in your .vmx file <--



VMWARE Player -- (FREE) This can play any VM created with the server or more advanced workstation and gsx products. It can also play Microsoft VM created machines. The idea is you can give customers a demo to run which is pre-built and runs in its own virtual machine. Slick.

GXS, Enterprise, etc. -- This is the real bread and butter for VMWARE as a company. These tools allow you to take racks and racks of computer hardware and treat it like a bit pool of computing power, allocating virtual servers as needed.