BootCamp changes the equation. Why would a "switcher" buy an underpowered MacBook when an Acer notebok computer could give him better Windows performance for far less money?
Apple needs to release computers that run Windows AS WELL AS or BETTER THAN their competitors. This will make it easy for switchers to come to Apple for uncompromised Windows performance... after which they will spend more and more time in MacOS X once they experience its advantages over Windows.
Apple should not release a computer that costs the same as a Windows box, but that runs Windows more slowly. Instead, Apple should release a computer that runs Windows as quickly as the competition, but that costs a little bit more because it adds the capability to run MacOS X.
If Apple handles the Intel transition well, it can ironically become the "high performance" computer choice for Windows users, can maintain its profit margins, AND can draw some market share over to MacOS X.
A "too-expensive" but fast and full-featured MacBook might make some Apple fans grumble, but would in the long run do Apple's market share far more good than a computer that competes on price with Windows boxes, but that doesn't compete on Windows performance.