When Vista is launched, Microsoft will take XP off the shelves. You won’t be able to buy a (ahem, legal) copy of Windows XP for love nor money.
Most business’s don’t migrate to a new OS version overnight, so they’ll be wanting legal copies. ‘Pro-sumer’ users who buy new systems may want to dual-boot Windows XP if Vista isn’t compatible with their existing software or hardware. And with such radical changes, there may even be ‘normal’ people who just prefer to stick with what they’re used to and thus will want to downgrade their new systems to XP.
The answer, the original blog poster raises, might be to buy shrink-wrapped Win XP now, and sell it on at a profit when Vista ships. Interesting.