There are a couple of reasons you may want to do this. In Linux there are just some things you're not able to do without going into Windows: one of those is Microsoft Office 2010, which struggles with Wine. If you'd like to have Windows and possibly other operating systems at your fingertips though, let us continue with the tutorial for setting up Virtual Machines in Linux Mint 11.
Go to the Software Manager located in the Menu. Search for "virtualbox-ose" and install it:
Now go to Menu -> Accessories -> VirtualBox OSE
Select "New" to begin the process of creating a new virtual machine. Press Next until you get to the following screen and select the operating system you want to use and name your virtual machine.
Now we'll want to designate how much RAM to allow your system to have, if you can afford it 1024 MB is a good amount for a Windows 7 system. Otherwise 512 is the minimum recommended by VirtualBox. Using the slider move it to the amount of RAM you'll be using:
Next we'll want to create a new boot hard disk for our operating system files and other programs to be stored on. We'll do that by clicking "Create new hard disk."
Next we'll have to choose which type of hard disk our operating system gets. The options are "Dynamically Expanding Storage" and "Fixed-Size Storage." With both of these, you will specify the size that Windows will think the drive is, but the Fixed-Size Storage one starts out the same size that you specify immediately taking up the maximum amount the virtual box is capable of.
Once you have decided the type of drive to make, you will be asked to assign the maximum amount of space to the system. You should choose this amount based on what you plan on doing with your Windows system, considering that it is difficult to get 3D acceleration to work in emulated systems though and that many games may not work.
Hit Next a couple of times to finish out the menu and you will be brought back to the main menu with our newly created blank Virtual Machine.
Next, we'll want to select the boot disk for the CD/DVD disk (or ISO) that we will be installing Windows from. To do this, select Settings from the screen above, go to Storage on the left side and under IDE Controller select "Empty." Now under Attributes on the right hand side, choose the appropriate CD/DVD drive that corresponds to your drive, or if you're using an ISO file click on the picture of the CD, select "Choose a virtual CD/DVD disk file..." and then navigate to the location of your ISO.
Once your CD is mounted you should be brought back to the main screen. Click start, to boot up into the Windows installation, from here you should see the familiar screen that looks like the one below:
Follow the windows installation like you would normally install it. Once it is done, you'll automatically boot into Windows. If you'd like you can unmount your installation CD now by right clicking on the single CD icon at the bottom right of the window and selecting "Remove disk from virtual drive."
Now, for additional functionality (such as allowing Seamless Display and Shared Folders) if you press Host Key (Right CTRL by default) + D you will begin the process of downloading and installing the VirtualBox Guest Additions.
Say Yes, when prompted to download the ISO from the internet. Another prompt will appear, asking you to download it. Click that and then you'll be asked if you wish to mount the ISO. Click, mount and wait for autoplay to appear. Install the windows application like normal.
Reboot your virtual machine and enjoy the new features accessible from the menu. Some features that you may enjoy are Seamless Mode (Host Key + L) with certain applications or full screen mode. To get a shared folder working, you will want to right click on the folder in the bottom tray of the operating system window and click on "Shared Folders..." and then select Add Shared Folders (Ins):
From here, you can find a directory that you want to have windows recognize from your Linux box as a network drive. For folder path, if you select "Other..." you will gain access to a file browser. Auto-Mount will make the drive mount upon start.
That concludes the basics of VirtualBox. Below I have included a picture of Windows 7 running in Seamless Mode in Linux Mint 11. The only program I have running in it is Internet Explorer 9. Getting Microsoft Office 2010 is easy to get installed at this point. You just install it from the CD or the executable file found from Microsoft's website. This is particularly helpful for students looking to run OneNote 2010 in Linux.