Hate to sound like a fanboy, but I've been doing virtualized XP on Linux for YEARS. With VirtualBox. And SeamlessRDP, so my Windows apps look like they are just running on Linux.
Microsoft does it for backward compatibility in a half ass'd fashion, and only including it with their top-tier (ie: most expensive) products and it's suddenly the Greatest Thing(tm) since sliced bread?
Linux - Free
VirtualBox - Free
Reliability factor: Unbelievable. And just as fast.
How often I use it: Rarely. But if I had that one app that had to run on Windows XP, I can.
Microsoft has jumped the shark. They release Windows just because they have nothing else worth doing. And Windows is fast becoming not worth the effort. Since W2k, their product has steadily gone to hell.