Should you migrate away from XP now?

I suggest you do not plan to migrate now for at least one good reason. The number of satisfied installed XP users is very large. These present a business opportunity to innovative entrepreneurs. Surely someone will find a way of providing at least a measure of XP support, should Microsoft actually be brave enough to pull the plug. I suggest you wait until 2014 and see what offers are available at that time.
I worked for IBM for many years and they suffered from customers who wanted to keep 80 column Card Readers on rental for ever. IBM's approach, which I commend to Microsoft, is not to pull any plugs, but to progressively increase the cost to customers until they finally choose to migrate. Never tell your customer what he should do if you want to stay in business. Why Microsoft haven't already introduced a small annual charge for XP support, I will never understand.