Now that we have created a VM (including the virtual hard disk) for Windows XP, we need to tweak some settings. You should be back to the main VirtualBox window with your new VM highlighted. Click the Settings button in the navigation bar to open the settings window for the XP VM.
You'll now see the Basic tab of the General page. Here, you can change the Name, Operating System, and Version. We just set those options when we created the VM, so ignore this page and open the System page in the left pane.
Now we're on the Motherboard tab, which houses options for adjusting the VM's Base Memory, Boot Order, and Extended Features. We do not need to change any of these options, so click the Processor tab. If you're lucky enough to have a sickening amount of system RAM (enough to give your VM 4GB or more), you will need to check the box next to Enable PAE/NX in order for a 32-bit OS on your VM to address that much. Click on the Acceleration tab to continue.
If your CPU has hardware-accelerated virtualization capabilities, you will want to check the box next to Enable VT-x/AMD-V so that the VM can utilize them to boost performance. If your CPU has nested paging capabilities, check the box next to Enable Nested Paging for another performance boost. If your CPU doesn't have either of these, the selections will be grayed out.
Click the Display option so that we can adjust the Video Memory Size. My PC has up to 128MB of video memory that I can allocate to the VM. You can choose whatever size that you think you'll need. A good rule of thumb is that the more high-resolution gaming you do, the more video memory you'll want to allocate. Also click on the checkbox next to Enable 3D Acceleration if you anticipate any gaming.
Next, click on the CD/DVD-ROM page in the left pane. We need to check the box next to Mount CD/DVD-ROM. Now, check the box next to Host CD/DVD Drive. If you have multiple optical drives, select the one you will use to install Windows XP from the drop-down menu. If you have your Windows XP disc handy, insert it into your optical drive of choice. If your file manager automatically opens after inserting the disc, simply close it.
Before we're ready to install XP, we need to set up a folder to share files between the Linux host OS and the XP guest OS. Click the Shared Folders page in the left pane. First, click on the Add button on the far right (blue folder with green plus sign) to open the Add Share window. Next, click on the drop-down menu next to the Folder Path field, then choose Other. Now, find or create a folder in your Ubuntu file tree where you want data to be shared with your XP installation. I chose the Public folder in my Home directory located at /home/adam/Public. Click Open, and then OK. Wherever you create that shared folder, make sure you remember where it is. Click OK to finish tweaking the Windows XP VM's settings.