This solution works, isn't choppy on my computer. It is, however a bit clunky. You need to grab your Windows XP disk (or find a lightweight version off of bittorrent or something, the lighter the better) and that's all you will need.
Now you need to go on and install Virtual Box. You can install this by using Ubuntu Software Center (Top bar -> Applications -> Ubuntu Software Center).
After that it's pretty easy to use. I recommend using dynamic disk size and 1GB of RAM. I have experienced little to no choppyness with this setup.
To install the operating system use your XP disk or ISO image with the NEW button at the top.
After you've set everything up (and don't forget to download silverlight) you can use something called "seamless mode" which will take it out of window mode and the whole operating system will act like it is part of ubuntu. You can enable this from the File menu or using (right)Ctrl + L.