Open Synaptic Package Manager, search for "VirtualBox", and click on the checkbox to the left to install it

It's the Virtual Machine I recommend for a variety of reasons.
Once installed, go through the settings *first*, and enable things like CD/DVD access, network access, usb access, etc... that you'll want your Virtual Windows to have. Then, make sure that your Windows cd is in your *1st* CD/DVD drive, and make a new Machine. Call it what you'd like - "Windows", etc... but something to distinguish it. It'll ask you what environment you'll be running - scroll down to Windows (XP? I can't remember if that's an option - if it is, choose it

). Then, you'll set up your virtual hard drive - set it to dynamic, which it is by default, so it can "grow" if it needs to, then it'll as for memory (512 Megabytes if great if you can spare it), etc... just check the best options.
Then, you'll boot into the virtual machine you just made. BE QUICK HERE! After the "Innotek...." screen, you'll get a *very* brief opportunity to press F12, and point your Virtual Machine to boot from the CD drive, so make sure you already have a finger on F12 and hit it when it pops up

And that's it. It installs in it's own, protected-from-Linux, seperate virtual machine, which you can boot into anytime to run your windows apps

You can also install all of the Microsoft updates, an antivirus (I recommend the free Avira Antivir), etc... and you're good to go.
Oh, and the full-screen it on a desktop, and spin your cube around and watch XP go by...
