Does contrast ratio and response time really matter?

Don't even bother to look at the contrast ratio for the monitors. It's very hard to actually measure what the contrast ratio of a screen actually is, so those ratings don't really tell you what it is.
As for response time, it doesn't really matter at those speeds anyway. The human eye can only notice about a 16ms response time(which is 60Hz), so you shouldn't notice the difference between the two monitors response times.