Is there a substantial difference in a 2.2 ghz and 2.4 ghz processor?

Nope, not really.

Technically, it’s 9% faster, but only when the processor is the bottleneck, which it will rarely be on a notebook with a 5400 RPM hard drive, 667MHz memory, and a 800MHz bus. The vast majority of the time those extra processor cycles will be idling.

That depends on how much video rendering you do. Other than that, not much.

It’s true that video rendering will push your processor’s clock to the limit, but if you’re planning on doing a lot of video rendering, a MacBook is probably not the right machine for you.

I strongly doubt there would be a noticeable difference between the two. Even when using the computer to its fullest potential, it wouldn’t be the processor holding it back from going further, it would probably be the memory (since. its slow, in comparison to the bus speed of the processor). In essence, even though you would have .3 more ghz’s processing power, your computer wouldn’t be able to “think it” quite so quickly, because of that delay.
Also, because the hard drive on the macbook is 5400 as previously stated, the computer wouldn’t be able to do anything with that data as quickly as it was thought out either.
To summarize: 2.4 would be, in practice, overkill.

Apple tends to bundle specs into groups, so while the actual difference in processor speed is small, going to the lower speed might also reduce hard drive size or RAM. Watch out for unacceptable changes.

about 200 Mhz
;-)