When you get back to the Ubuntu desktop you can now open VirtualBox via Applications/SystemTools/SunVirtualBox. Since we are using the free version of Sun VirtualBox, and not the free and open-source version, we need to agree to the license agreement. To do this, scroll all the way down and then click I Agree.
Next, the VirtualBox Registration Dialog window should open. If you already have a Sun Online account, enter your email and password and click Register. If not, you can enter your information and click Register. Alternatively, you can also just click Cancel to continue. Once VirtualBox opens, click on the New button in the navigation bar. This opens the Create New Virtual Machine wizard. Click Next.
In the Name field, enter a name for your new virtual machine. If you plan on having several VMs, name each VM descriptively to avoid confusion (such as “Windows XP SP3 32-bit”). You could also name the VM for its intended purpose, such as “Gaming,” “MS Office,” or “Compatibility Testing.” Under OS Type, you can choose the operating system and version. Since VirtualBox defaults to Microsoft Windows in the Operating System field and Windows XP in the Version field, we can leave it alone and click Next.
Now we must decide how much system memory we want to allocate to the virtual machine. In this respect, the VM is much like a real system; the more memory, the better. You can allocate up to half of your system's RAM to the VM. My test system has 4GB, so I'm going to give 1GB to the Windows XP VM. This will leave the host OS (Ubuntu) with 3GB when XP is running. After you have decided how much RAM to give to your VM, click Next.
Since this is the first time you're running VirtualBox, there won't be any virtual hard disks to chose from. Therefore, we must select Create new hard disk, and then click Next. This opens the Create New Virtual Disk wizard. Click Next again.
On this screen, we are presented with the choice between Dynamically expanding storage and Fixed-size storage. The difference is that Dynamically expanding storage will only take up the amount of space used by data in the VM. Fixed-size storage immediately takes up the entire size of the virtual disk. With either option, you will need to specify the size of the virtual disk after clicking Next.
The Location field on this page should already be indicating the name that you gave the VM earlier. Using either the text box or the slider, you can specify the size that you want your virtual hard disk to be. Remember, if you chose Fixed-size storage, your real hard disk will lose whatever amount you decide here. If you chose Dynamically expanding storage, this is the maximum amount of space your virtual hard disk will be allowed to consume. I'm happy with the default size of 10.00GB, but you can specify any size that works for you. Click Next.
The Summary Screen will display the type and size of your virtual hard disk as well as it's location on your real hard drive. Verify that the options are correct, and perhaps make note of the virtual disk's location. This is a good idea in case you want to backup, or even take your virtual hard disks with you. When satisfied, click Finish. The more space you've given to Fixed-size storage, the longer this will take. After your virtual hard disk is created, that wizard will close and another summary screen will display the Name, OS Type, Base Memory, and Boot Hard Disk that you selected for your new virtual machine. Verify the information and then click Finish.