I'm not sure you understand the difference between dual booting and using a virtual machine (Or thats how it reads). Dualbooting is where your computer can start, in this case, either Windows XP or Ubuntu when it boots up.
A virtual machine is where you've started XP and you use Ubuntu inside this, using a virtual machine.
A virtual machine can use the internet, install and everything else. It will take a major performance blow though; I'm not even sure if it'll work at all on your computer. If it does it wont be any fun.