Having worked with virtualization software since prehistoric times… (yes, Quarterdeck DeskView and QEMM) it only has really worked for me with machines with expanded RAM. We have come a long way. The best recommendation I can give is that if you are hosting on Windows, that you would do well to have 4-8 gigs of RAM. You need to have enough RAM to comfortably run the host operating system as well as the guest operating system(s). This may be less of a problem for older guests, and maybe Linux, without a GUI (we’ll see …).

If you are expecting to be productive on the host machine when running a large guest OS, you need the RAM. For example, on my 4 gig iMac, I don’t do much in the way of Mac stuff, when I’m running Windows 7 via Parallels, and I’ve only allocated 1.5 gigs of memory to the Windows guest… so Windows doesn’t perform particularly well either.

On the other hand with my recent Windows 7 box with 8Gigs, I’ve been going to town hosting multiple Linux versions, as well as Windows 7 and 8 guests. In these cases I’m able to allocate 2-4 gigs to each guest.  

To get started with VirtualBox, you need to go to the website and download the version you want for your operating system. Examples here are from the Windows version. Mac and Linux versions behave similarly. Once installed and started you are shown the VB Manager.

Click to enlarge

The manager shows each virtual machine set up on the host in the left-hand pane, and then anything specific to a guest in the right hand pane. This includes all of the hardware specifications for the virtual hardware, as well as a screen shot of what is happening on the screen of the virtual machine.

The manager currently shows an instance of Red Hat Version 9 (Shrike) booting up. The preview screen is an echo of a full interactive screen which is present in its own window.  Below is an example of a Windows 7 guest running within a Windows 7 host. 

Cick to enlarge: Installing a Windows 7 guest

Guest operating systems can be installed from physical CD/DVDs, USB drives, or disk images (.iso files). Iso files are easiest, as you don’t have to worry about the VirtualBox host using external hardware. 

For example for the Windows 7 installation shown above, I assigned the Windows installation .iso file by clicking on the disk in the upper right-hand corner in the VirtualBox manager. 

Click to enlarge: Choose an disk image for installing an OS